Magnetochemistry

9 pages, 1619 KB

Open AccessArticle

Magnetic Anisotropy Vectors and Mixing of Spin-States Across Spin Transition in [Mn^III(pyrol)₃(tren)] Explored with Polarized Neutron Diffraction

by Pikesh Pal, Iurii Kibalin, Arsen Goukassov, Thomas C. Hansen, Eddy Lelièvre-Berna, Yann Garcia and Grégory Chaboussant

Magnetochemistry 2026, 12(5), 56; https://doi.org/10.3390/magnetochemistry12050056 (registering DOI) - 12 May 2026

Abstract

[Mn^III(pyrol)₃(tren)] {(Hpyrol)₃tren = tris(1-(2-azolyl)-2-azabuten-4-yl)amine)} is a mononuclear spin-transition compound switching between high spin (HS, S = 2) and low spin (LS, effective S = 1) around 47 K, preserving I

\bar{4}

3d symmetry. Its magnetic [...] Read more.

[Mn^III(pyrol)₃(tren)] {(Hpyrol)₃tren = tris(1-(2-azolyl)-2-azabuten-4-yl)amine)} is a mononuclear spin-transition compound switching between high spin (HS, S = 2) and low spin (LS, effective S = 1) around 47 K, preserving I

\bar{4}

3d symmetry. Its magnetic anisotropy is studied by calculating the atomic susceptibility tensor from the refinement of polarized neutron powder diffraction. The analysis reveals that the weakly prolate-type atomic magnetic anisotropy in the HS state abruptly switches to uniaxial needle-shaped/Ising-type anisotropy in the LS state. However, the overall magnetic anisotropy of the unit cell remains isotropic due to the cubic nature of the crystal symmetry. Irreversible coexistence of mixed spin states HS/LS is observed in the vicinity of the cooperative spin crossover, where the average magnetic moment of Mn³⁺ shows a hysteretic temperature variation. This hysteretic mixing of HS and LS at intermediate temperatures suggests complex growth and nucleation of HS and LS domains. The study demonstrates that polarized powder neutron diffraction is a unique and powerful tool for describing complex magnetic anisotropies and magneto-structural correlations in molecular-based magnetic materials. Full article

(This article belongs to the Section Molecular Magnetism)

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25 pages, 10124 KB

Open AccessArticle

Laser-Engineered Co/Cu Multilayers by Pulsed Laser Deposition: Interfacial Control, Spin-Dependent Transport, and Enhanced Giant Magnetoresistance

by Cătălin-Daniel Constantinescu, Eros-Alexandru Pătroi, Nicu-Doinel Scărișoreanu, Antoniu-Nicolae Moldovan, Anca-Gabriela Nedelcea, Cătălin-Romeo Luculescu, Cosmin Cobianu, Maria-Cătălina Petrescu and Lucian-Gabriel Petrescu

Magnetochemistry 2026, 12(5), 55; https://doi.org/10.3390/magnetochemistry12050055 (registering DOI) - 9 May 2026

Abstract

Cobalt/copper (Co/Cu) multilayers are prototypical systems for giant magnetoresistance (GMR)-based spintronic devices, where interfacial quality and spin-dependent scattering critically determine performance. In this work, Co/Cu multilayers were fabricated by pulsed laser deposition (PLD) on SITAL ceramics, Si(100), and BK7 substrates, with 10, 20, [...] Read more.

Cobalt/copper (Co/Cu) multilayers are prototypical systems for giant magnetoresistance (GMR)-based spintronic devices, where interfacial quality and spin-dependent scattering critically determine performance. In this work, Co/Cu multilayers were fabricated by pulsed laser deposition (PLD) on SITAL ceramics, Si(100), and BK7 substrates, with 10, 20, and 40 bilayer repetitions, in order to elucidate the interplay between microstructure, interfacial diffusion, and magnetotransport properties. Systematic characterization combining atomic force microscopy (AFM), scanning electron microscopy (SEM), SIMS/SNMS depth profiling, vibrating sample magnetometry (VSM), and Hall effect measurements reveals that PLD enables controlled multilayer growth with low background roughness and well-defined periodic structures, despite the presence of characteristic particulates. A clear dependence of the GMR response on both bilayer number and substrate type is observed. Increasing the number of repetitions enhances spin-dependent scattering at Co/Cu interfaces, leading to a progressive increase in the magnetoresistance amplitude, reaching ~−14% for 40-period multilayers on SITAL substrates. This enhancement is attributed to the higher interface density and improved interfacial coherence, as confirmed by SIMS/SNMS analysis showing reduced interdiffusion in thicker stacks. In parallel, Hall effect measurements indicate a reduction in carrier density and an increase in carrier mobility with increasing multilayer thickness, consistent with improved charge transport stability. A pronounced substrate effect is demonstrated: SITAL-supported multilayers exhibit enhanced GMR sensitivity (up to ~44%·T⁻¹) due to increased diffuse spin-dependent scattering at rougher interfaces, whereas Si(100) substrates promote smoother growth, improved structural coherence, and more stable electronic transport. While sputtering typically enables smoother interfaces and higher GMR ratios, PLD offers enhanced flexibility in tailoring interfacial morphology and diffusion processes, which can lead to improved sensitivity under specific conditions. These results establish PLD as a versatile route for tailoring Co/Cu multilayers, enabling controlled optimization of the trade-off between sensitivity and structural quality for advanced spin-valve and magnetic sensor applications. Full article

(This article belongs to the Special Issue Magnetic Materials, Thin Films and Nanostructures—2nd Edition)

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29 pages, 3050 KB

Open AccessReview

Progress on Experimental Techniques for T₁-T₂ 2D NMR Measurements in Tight Oil Reservoirs—A Review

by Xiulan Zhu, Yanju Li, Chaoqun Ren, Zhanjun Chen, Tai Xu, Anzhao Ji and Changrui Kou

Magnetochemistry 2026, 12(5), 54; https://doi.org/10.3390/magnetochemistry12050054 - 7 May 2026

Abstract

The microscopic pore structure and fluid occurrence laws of tight oil reservoirs are intricate, leading to relatively low oil production rates. The T₁-T₂ two-dimensional nuclear magnetic resonance (2D NMR) technique presents significant advantages for fluid identification and the quantitative characterization [...] Read more.

The microscopic pore structure and fluid occurrence laws of tight oil reservoirs are intricate, leading to relatively low oil production rates. The T₁-T₂ two-dimensional nuclear magnetic resonance (2D NMR) technique presents significant advantages for fluid identification and the quantitative characterization of fluids and pore spaces in these reservoirs. Nonetheless, systematic and in-depth investigations into its experimental measurements remain scarce. A comprehensive review of both domestic and international literature on T₁-T₂ 2D NMR measurement techniques was conducted for oil reservoirs. The fundamental principles, data acquisition and inversion mechanisms of 2D NMR technology were elucidated. Additionally, the signal distribution laws of hydrogen-containing components under varying test parameters were summarized. The relationship between NMR experimental testing and reservoir characteristics was explored, elucidating the mechanism of the T₁-T₂ spectra. Building upon this foundation, the strategic optimization of data acquisition and inversion methodologies, along with critical parameters for T₁-T₂ NMR measurements, significantly enhanced the precision of NMR datasets and the fidelity of 2D NMR spectral imaging. These advancements provide a theoretical basis and technical support for the characterization of rock and fluid in tight oil reservoirs. Full article

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16 pages, 8444 KB

Open AccessArticle

Continuous Characterization and Classification of Carbonate Pore-Throat Structure Using an Artificial Neural Network

by Jue Hou, Lirong Dou, Lun Zhao, Yepeng Yang, Xing Zeng and Tianyu Zheng

Magnetochemistry 2026, 12(5), 53; https://doi.org/10.3390/magnetochemistry12050053 - 7 May 2026

Abstract

Pore-throat structures in a carbonate reservoir were classified into ten petrophysical facies representing coarse, medium, or fine throat types based on Mercury Injection Capillary Pressure (MICP) data from 77 core samples, directly reflecting distinct flow capacities. Using Nuclear Magnetic Resonance (NMR) data from [...] Read more.

Pore-throat structures in a carbonate reservoir were classified into ten petrophysical facies representing coarse, medium, or fine throat types based on Mercury Injection Capillary Pressure (MICP) data from 77 core samples, directly reflecting distinct flow capacities. Using Nuclear Magnetic Resonance (NMR) data from 20 samples, an artificial neural network (ANN) model was developed with four conventional logs, namely Gamma Ray (GR), Deep Laterolog Resistivity (RD), Density (DEN), and Compensated Neutron Log (CNL), as inputs to predict the T₂ spectrum continuously. A cumulative pore-throat size distribution matching method was then used to transform predicted T₂ spectra into capillary pressure curves. The resulting pore-throat parameters show excellent agreement with core measurements, with relative errors for key parameters—such as median pore-throat radius (R₅₀) and sorting coefficient (Sp)—below 15%. This approach extends discrete core data to continuous wellbore profiles, enabling pore-throat prediction and facies classification in intervals lacking MICP data. It effectively identifies dominant flow channels and tight interlayers, with facies validated by thin-section petrography, providing a robust basis for evaluating highly heterogeneous carbonate reservoirs. Full article

(This article belongs to the Special Issue Nuclear Magnetic Resonance (NMR) in the Petroleum Industry and Porous Media)

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16 pages, 3471 KB

Open AccessArticle

Preparation and Rheological Characterization of Double-Coated PAO-Based Magnetic Fluids

by Zhimin Sun, Feng Ren, Lan Mei, Jing Wang and Yuan Cheng

Magnetochemistry 2026, 12(5), 52; https://doi.org/10.3390/magnetochemistry12050052 - 6 May 2026

Abstract

Polyalphaolefin (PAO)-based magnetic fluids are widely used in precision transmission systems for their excellent rheological and lubricating properties, but their stability and magnetic controllability under high-temperature and high-shear conditions remain a key challenge. In this work, a PAO2-based magnetic fluid was prepared via [...] Read more.

Polyalphaolefin (PAO)-based magnetic fluids are widely used in precision transmission systems for their excellent rheological and lubricating properties, but their stability and magnetic controllability under high-temperature and high-shear conditions remain a key challenge. In this work, a PAO2-based magnetic fluid was prepared via coprecipitation using a sequential modification strategy involving oleic acid and alkenyl succinimide. An energy competition model under multi-field coupling was established using the magnetothermal energy ratio (

λ

) and Mason number (

M n

) to elucidate the system’s rheological behavior. The fluid shows significant shear-thinning behavior under zero magnetic field; a 60 kA/m magnetic field increases the relative viscosity by over 4 times at 5 s⁻¹, while the magnetoviscous effect becomes weak at shear rates over 500 s⁻¹ (corresponding approximately to

M n

= 1). With increasing temperature, the field-induced viscosity enhancement decreases progressively as thermal disturbance becomes increasingly important. This work reveals the multi-field coupling rheological mechanism, and the results suggest that the OA/T154 modification strategy is a feasible route for obtaining a PAO-based magnetic fluid that remains dispersible and magnetically responsive under the tested conditions. The study provides theoretical and experimental support for the design of intelligent lubricating materials. Full article

(This article belongs to the Special Issue Ferrofluids: Electromagnetic Properties and Applications)

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21 pages, 4166 KB

Open AccessArticle

Band Structure Calculations and Magnetic Properties of HoCo₃₋_xSi_x Compounds

by Coriolan Tiușan, Roxana Dudric, Maria Căpățînă, Radu George Hațegan and Romulus Tetean

Magnetochemistry 2026, 12(5), 51; https://doi.org/10.3390/magnetochemistry12050051 - 5 May 2026

Abstract

The structural and magnetic properties and band structure results of HoCo₃₋_xSi_x compounds are reported. First-principles GGA+U+SO calculations, compared with magnetometry experiments, provide deep insight on the magnetic properties of the HoCo₃ compound. They show that HoCo₃ is [...] Read more.

The structural and magnetic properties and band structure results of HoCo₃₋_xSi_x compounds are reported. First-principles GGA+U+SO calculations, compared with magnetometry experiments, provide deep insight on the magnetic properties of the HoCo₃ compound. They show that HoCo₃ is a robust ferrimagnet, with strongly localized Ho-4f moments in excellent agreement with neutron data and itinerant Co-3d magnetism, where inclusion of the interstitial contribution brings the Co moments into very good agreement with the experimental data. The electronic structure reveals sharp Ho-4f states well below E_F, exchange-split Co-3d bands crossing E_F, and noticeable Ho-5d–Co-3d hybridization that mediates the antiparallel Ho–Co coupling and explains the non-negligible interstitial moment, providing a consistent microscopic picture that supports the experimentally observed increase in magnetization upon Co-Si substitution. Metamagnetic transitions are shown in magnetization isotherms. The observed transitions are broad and can be explained by the distribution of internal magnetic fields which arises from differences in the local environments of cobalt atoms. The magnetic properties were correlated with the theoretical results. Two transitions were revealed below room temperature, one due to a transition to a noncollinear magnetic structure and the other due to a temperature-induced metamagnetic transition. Full article

(This article belongs to the Special Issue 10th Anniversary of Magnetochemistry: Past, Present and Future)

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11 pages, 10468 KB

Open AccessCommunication

Nuclear Magnetic Resonance Investigation of Hydrogen Displacement in Tight Sandstone

by Xinwei Shi, Zhichao Geng and Yanfeng Sheng

Magnetochemistry 2026, 12(5), 50; https://doi.org/10.3390/magnetochemistry12050050 - 5 May 2026

Abstract

Hydrogen (H₂) storage in subsurface formations has recently gained attention as a promising large-scale energy storage solution. Although previous studies have revealed distinct displacement behaviors between H₂ and other gases such as nitrogen (N₂) and carbon dioxide (CO [...] Read more.

Hydrogen (H₂) storage in subsurface formations has recently gained attention as a promising large-scale energy storage solution. Although previous studies have revealed distinct displacement behaviors between H₂ and other gases such as nitrogen (N₂) and carbon dioxide (CO₂) in high-permeability sandstones, the mechanisms governing H₂ migration in tight formations remain largely unexplored. To provide experimental observations that may help improve the understanding of H₂ migration in tight reservoirs, we conducted H₂ flooding experiments on a tight sandstone sample from the Ordos Basin under pore fluid pressures of 0.5, 1, and 2 MPa. Dynamic core flooding processes were monitored using a low-field nuclear magnetic resonance (NMR) analysis system. The capillary number (Nc) in this work ranged from 1.7 × 10⁻⁹ to 3.4 × 10⁻⁹, indicating a capillarity-dominated flow. H₂ saturation in the tight sandstone increased from 41.9% to 53.3% and then to 57.7% with increasing pore fluid pressure. Under a pore fluid pressure of 0.5 MPa, H₂ initially displaced water in small pores (T₂ < 10.5 ms), leading to prolonged fluctuations in water content over 136 min before significant displacement occurred in large pores (10.5 ms < T₂ < 6579.3 ms). In contrast, at a pore fluid pressure of 2 MPa, the water in large pores was more significantly impacted, with a marked decrease in water saturation observed after 8 min of flooding. These findings provide direct experimental evidence of pressure-dependent and pore-scale selective displacement patterns of H₂ in tight sandstone, offering new insights into the fluid dynamics that control hydrogen injectivity and storage efficiency in low-permeability reservoirs. Full article

(This article belongs to the Special Issue Nuclear Magnetic Resonance (NMR) in the Petroleum Industry and Porous Media)

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13 pages, 3105 KB

Open AccessArticle

Predicting Pt-195 NMR Chemical Shift in Pt(II)-Sn(II) Complexes

by Milena A. Pereira, Larissa P. N. M. Pinto, Hélio F. Dos Santos and Diego F. S. Paschoal

Magnetochemistry 2026, 12(4), 49; https://doi.org/10.3390/magnetochemistry12040049 - 13 Apr 2026

Abstract

Platinum chemistry covers a wide range of applications, including homogeneous and heterogeneous catalysis as well as cancer therapy. Numerous Pt complexes have been synthesized and studied in recent years, with NMR spectroscopy serving as the primary technique for structural characterization. The ¹⁹⁵Pt [...] Read more.

Platinum chemistry covers a wide range of applications, including homogeneous and heterogeneous catalysis as well as cancer therapy. Numerous Pt complexes have been synthesized and studied in recent years, with NMR spectroscopy serving as the primary technique for structural characterization. The ¹⁹⁵Pt nucleus has favorable features for NMR studies, being highly sensitive to ligand type and structural environment. From a computational perspective, factors such as solvent effects, relativistic corrections, and the electronic structure of the ligands strongly influence the calculated NMR parameters. Consequently, establishing a general computational protocol for ¹⁹⁵Pt NMR prediction remains a challenging task. In this work, we present a systematic validation and extension of our previously developed computational protocol, originally proposed for Pt(II) complexes, in studying ¹⁹⁵Pt NMR chemical shifts in Pt(II)-Sn(II) complexes. A benchmark set of 100 Pt(II)-Sn(II) complexes was analyzed, yielding good agreement with experimental data (R² = 0.86, MRD = 3.6%, MAD = 163 ppm), which is remarkable given the structural diversity and broad range of chemical shifts covered. Full article

(This article belongs to the Special Issue 10th Anniversary of Magnetochemistry: Past, Present and Future)

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15 pages, 2320 KB

Open AccessArticle

Electromagnetic Control of Ferromagnetic Particle Movement Using PID and PWM

by Jesús Alexis Salcedo Muciño, Juan Alejandro Flores Campos, Adolfo Angel Casares Duran, Juan Carlos Paredes Rojas, José Juan Mojica Martínez and Christopher René Torres-SanMiguel

Magnetochemistry 2026, 12(4), 48; https://doi.org/10.3390/magnetochemistry12040048 - 10 Apr 2026

Abstract

In this article, the motion control of ferromagnetic particles through varying a non-invasive magnetic field is addressed. Within an experimental test bench, three experiments are proposed to verify motion control, which consist of control of the distance between electromagnets, retention of particles over [...] Read more.

In this article, the motion control of ferromagnetic particles through varying a non-invasive magnetic field is addressed. Within an experimental test bench, three experiments are proposed to verify motion control, which consist of control of the distance between electromagnets, retention of particles over the flow, and manipulation of the direction of particle flow at a “Y”-type bifurcation emulating an “OR” gate. At each experimental stage, instrumented test benches were integrated with current, distance, and flow sensors, enabling measurement and feedback of the system’s physical variables. These benches were configured using pulse-width-modulation (PWM) and Proportional–Integral–Derivative (PID) controllers to regulate the current supplied to the electromagnets and, thereby, control the intensity of the induced electromagnetic field according to the requirements of each experiment. Different study cases were defined to analyze the operational limits of the system by varying the current influencing the electromagnetic field and the configuration of the electromagnets. The results describe the response of the magnetic field, the induced force, and the behavior of the suspended particles under each condition, providing elements to characterize the performance of the electromagnetic system in operational scenarios and contributing to the understanding of the phenomena associated with the non-invasive manipulation of ferromagnetic particles by means of controlled magnetic fields. Full article

(This article belongs to the Topic Magnetic Nanoparticles and Thin Films)

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39 pages, 7931 KB

Open AccessArticle

First-Principles Insights into Cr- and Mn-Doped Rocksalt ScN: Engineering Structural Stability and Magnetism

by Ahmad M. Alsaad

Magnetochemistry 2026, 12(4), 47; https://doi.org/10.3390/magnetochemistry12040047 - 7 Apr 2026

Abstract

The study presents a comprehensive first-principles investigation of the structural, electronic, and magnetic properties of rocksalt scandium nitride (ScN) and its Cr- and Mn-doped derivatives using spin-polarized density-functional theory within the GGA + U (U_Cr = 3.5 eV, U_Mn = 2.7 [...] Read more.

The study presents a comprehensive first-principles investigation of the structural, electronic, and magnetic properties of rocksalt scandium nitride (ScN) and its Cr- and Mn-doped derivatives using spin-polarized density-functional theory within the GGA + U (U_Cr = 3.5 eV, U_Mn = 2.7 eV) and HSE06 frameworks. Pristine ScN crystallizes in the cubic Fm

\bar{3}

m structure and exhibits narrow-gap semiconducting behavior, with an indirect band gap of 0.82 eV obtained from hybrid-functional calculations, in excellent agreement with reported theoretical values. Substitutional doping with Cr and Mn introduces localized 3d states near the Fermi level, driving a transition toward spin-polarized metallic or half-metallic behavior accompanied by robust ferromagnetism. Density-of-states and band-structure analyses reveal that magnetism and charge transport in the doped systems are dominated by exchange-split transition-metal 3d states hybridized with N-2p orbitals. Total energy calculations confirm ferromagnetic ground states for both Cr- and Mn-doped ScN, with Mn substitution yielding stronger exchange stabilization and higher magnetic moments. Magnetocrystalline anisotropy energies, evaluated using the force-theorem approach, are found to be negligibly small, indicating weak anisotropy consistent with the moderate spin–orbit coupling strength in ScN-based nitrides. Nevertheless, symmetry breaking around dopant sites gives rise to a finite Dzyaloshinskii–Moriya interaction, leading to weak spin canting and non-collinear magnetic tendencies. The interplay between magnetic exchange coupling, spin–orbit interaction, and local inversion symmetry breaking positions of Cr- and Mn-doped ScN as promising dilute magnetic semiconductors with tunable spin polarization and chiral magnetic interactions, offering a viable platform for nitride-based spintronic and magneto-electronic applications. Full article

(This article belongs to the Section Magnetic Materials)

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13 pages, 3249 KB

Open AccessArticle

Enhancing Magneto-Optical Performance in LaFeO₃ Thin Films via Cubic-Phase Transition Induced by Ce³⁺/Ti⁴⁺ Co-Doping

by Zhuoqian Xie, Chenjun Xu, Yunye Shi, Nanxi Lin and Qisheng Tu

Magnetochemistry 2026, 12(4), 46; https://doi.org/10.3390/magnetochemistry12040046 - 7 Apr 2026

Abstract

Birefringence, arising from the low-symmetry structure in orthorhombic LaFeO₃, limits the observation and utilization of magneto-optical effects. In this study, the pure-phase perovskite-typed La₁₋_xCe_xFe₁₋_xTi_xO₃/SiO₂ thin films were successfully [...] Read more.

Birefringence, arising from the low-symmetry structure in orthorhombic LaFeO₃, limits the observation and utilization of magneto-optical effects. In this study, the pure-phase perovskite-typed La₁₋_xCe_xFe₁₋_xTi_xO₃/SiO₂ thin films were successfully fabricated via radio-frequency magnetron sputtering, where the co-doping of Ce³⁺ and Ti⁴⁺ ions effectively induced a structure transition from orthorhombic to a highly symmetric cubic phase, eliminating birefringence effect and thus reducing optical transmission loss. At the same time, the doped Ce³⁺ ions also effectively enhanced the magnetic and magneto-optical effects of the system due to their strong spin coupling effect and superexchange interaction with Fe³⁺ ions. The results show that the cubic-phase La_0.5Ce_0.5Fe_0.5Ti_0.5O₃/SiO₂ thin film exhibits excellent magnetic and magneto-optical performance. Their saturation magnetization reaches 180 emu/cm³ with an in-plane easy magnetic axis. And their magnetic circular dichroic ellipticity |ψ_F| reaches 3054 degrees/cm. Full article

(This article belongs to the Section Magnetic Materials)

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9 pages, 1404 KB

Open AccessArticle

Impact of O/S Substitution on Ligand Field and Single-Ion Magnetic Properties of Co(II) N₃⁻-Containing Octahedral Complexes

by Yan-Fang Wu, Zheng Huang, Jing Wei, Rong-Jie Hao, Jia-Ying Wang, Yan Peng, Ning Song, Zhao-Bo Hu, Yu-Hui Tan and Yun-Zhi Tang

Magnetochemistry 2026, 12(4), 45; https://doi.org/10.3390/magnetochemistry12040045 - 7 Apr 2026

Abstract

Electronics evolution drives SMMs as a frontier, overcoming conventional magnetic material limits via molecular spin coupling. Two relevant Co(II) mononuclear complexes, [Co(MOP)₄(N₃)₂] (1) and [Co(MSP)₄(N₃)₂] (2) (MOP [...] Read more.

Electronics evolution drives SMMs as a frontier, overcoming conventional magnetic material limits via molecular spin coupling. Two relevant Co(II) mononuclear complexes, [Co(MOP)₄(N₃)₂] (1) and [Co(MSP)₄(N₃)₂] (2) (MOP = 4-methoxypridine and MSP = 4-methylthiopyridine) were synthesized through changing the substituents of ligands. The Co(II) ions in the two complexes show octahedron coordination geometries. The replacement of the O to S in the equatorial plane leads to different Jahn–Teller effect because of the shorter Co(II)-N in the equatorial plane, resulting in the significantly different slow relaxation process confirmed by ab initio calculation. The results confirm the Co(II) ion is sensitive to ligand field. Full article

(This article belongs to the Section Molecular Magnetism)

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Graphical abstract

9 pages, 23038 KB

Open AccessArticle

Effect of Cu Element Addition on Soft Magnetic Properties of Fe-Gd-B Alloys

by Linli Wang, Yongchun Liang, Feng Huang, Yingchao Yue and Xiaoyu Luo

Magnetochemistry 2026, 12(4), 44; https://doi.org/10.3390/magnetochemistry12040044 - 2 Apr 2026

Abstract

In order to conduct a systematic study on the influence of the copper element on the soft magnetic properties of alloys, a series of alloy ribbons with compositions of Fe_90.70−xGd_2.32B_6.98Cu_x (x = 0.25, 0.5, [...] Read more.

In order to conduct a systematic study on the influence of the copper element on the soft magnetic properties of alloys, a series of alloy ribbons with compositions of Fe_90.70−xGd_2.32B_6.98Cu_x (x = 0.25, 0.5, 0.75, 1.0, 1.25, and 1.5) were fabricated via the single-roller melt-spinning method. The microstructure and magnetic properties of these ribbons were systematically characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and vibrating sample magnetometry (VSM). The research findings indicate that the introduction of the copper element significantly enhances the soft magnetic properties of the alloys. For the alloy ribbon with the optimized composition of Fe_89.95Gd_3.32B_6.98Cu_0.75, the saturation magnetization (B_s) attains 1.74 T. The improvement in performance is primarily attributed to the precipitation of the nanocrystalline α-Fe phase. This phase features fine grain sizes and relatively wide magnetic domain structures, which contribute to an increase in the saturation magnetization and a reduction in the coercivity, thus comprehensively optimizing the soft magnetic properties of the alloys. Full article

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13 pages, 2699 KB

Open AccessArticle

Tailoring Microstructure Orientation and Magnetic Properties in AlNiCo Permanent Magnets by Controlled Withdrawal Rate in High-Rate Solidification

by Qilong Wu, Zhuo Sun, Anjian Pan, Huidong Qian, Yixing Li, Jinkui Fan, Jiantao Feng, Lizhong Zhao, Zhongwu Liu and Xuefeng Zhang

Magnetochemistry 2026, 12(4), 43; https://doi.org/10.3390/magnetochemistry12040043 - 2 Apr 2026

Abstract

Enhancing grain orientation along the <001> crystal axis in AlNiCo alloys is crucial for developing high-performance permanent magnets. Traditional directional solidification, known as the “cold plate-hot mold” method, is constrained by a low thermal gradient, leading to inadequate microstructural uniformity and crystallographic alignment, [...] Read more.

Enhancing grain orientation along the <001> crystal axis in AlNiCo alloys is crucial for developing high-performance permanent magnets. Traditional directional solidification, known as the “cold plate-hot mold” method, is constrained by a low thermal gradient, leading to inadequate microstructural uniformity and crystallographic alignment, which impedes the optimization of magnetic properties. In this study, we employed a high-speed solidification process with an enhanced cooling gradient to fabricate AlNiCo magnets at various withdrawal rates. The variation in drawing rate influenced grain orientation within the alloy, thereby altering the degree of alignment of the ferromagnetic α1 phase following subsequent heat treatment, which ultimately affected the magnetic properties. The optimal magnetic performance was attained at a withdrawal rate of 50 μm/s, where the sample exhibited the most favorable oriented microstructure, with a remanence (B_r) of 10.62 kGs, intrinsic coercivity (H_cj) of 1.794 kOe, and a maximum energy product (BH)_max of 10.93 MGOe. Moreover, magnets at different positions exhibit excellent consistency in magnetic properties, enhancing the material utilization efficiency. This research provides valuable process parameters and a foundational basis for developing high-performance AlNiCo alloys. Full article

(This article belongs to the Section Magnetic Materials)

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16 pages, 4461 KB

Open AccessArticle

The Influence of Tooth Shape on Pressure Transmission Capacity in Magnetic Fluid Sealing

by Jiahao Dong, Hao Lu, Zhenfei Shen and Zhenkun Li

Magnetochemistry 2026, 12(4), 42; https://doi.org/10.3390/magnetochemistry12040042 - 2 Apr 2026

Abstract

Magnetic fluid sealing is an ideal solution for high-end equipment. However, traditional rectangular pole teeth suffer from low magnetic flux utilization and insufficient pressure resistance. Meanwhile, the pressure transmission mechanism of different pole teeth and the evolution law of magnetic fluid boundary morphology [...] Read more.

Magnetic fluid sealing is an ideal solution for high-end equipment. However, traditional rectangular pole teeth suffer from low magnetic flux utilization and insufficient pressure resistance. Meanwhile, the pressure transmission mechanism of different pole teeth and the evolution law of magnetic fluid boundary morphology remain unclear, restricting structural optimization. This study investigates rectangular and trapezoidal pole teeth by adopting the Volume of Fluid model, combined with finite element simulation and experimental verification. A sealing simulation model and a dedicated experimental platform were established to systematically explore the effects of the two pole tooth types on pressure transmission efficiency and magnetic fluid boundary morphology under static and dynamic sealing conditions, as well as their pressure resistance and self-recovery characteristics. Results show that trapezoidal pole teeth exhibit superior pressure resistance to rectangular ones due to optimized magnetic field distribution: the maximum static sealing pressure resistance increases by 40.9 kPa, and the dynamic sealing pressure resistance at 8000 rpm rises by 63.2 kPa. The 2% deviation between simulation and experimental data verifies the model’s reliability. This work clarifies the intrinsic relationship between pole tooth structure and sealing performance, reveals the pressure transmission mechanism of different pole teeth, and provides theoretical and engineering references for pole tooth structural optimization, which is significant for improving the pressure resistance stability and engineering applicability of magnetic fluid sealing. Full article

(This article belongs to the Special Issue Ferrofluids: Electromagnetic Properties and Applications)

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10 pages, 2889 KB

Open AccessArticle

Nanocolumnar ZnO/Fe Magnetic Composites

by Andreas Kaidatzis, María Garrido-Segovia, José Miguel García-Martín, Nikolaos C. Diamantopoulos, Dimitrios-Panagiotis Theodoropoulos and Panagiotis Poulopoulos

Magnetochemistry 2026, 12(4), 41; https://doi.org/10.3390/magnetochemistry12040041 - 1 Apr 2026

Abstract

Composite ZnO/Fe nanostructured thin films are synthesized via physical vapor deposition using radio frequency magnetron sputtering in conventional, as well as in glancing angle deposition (GLAD) geometries. ZnO is employed as a compact nanocolumnar template to direct Fe growth in bilayer and multilayer [...] Read more.

Composite ZnO/Fe nanostructured thin films are synthesized via physical vapor deposition using radio frequency magnetron sputtering in conventional, as well as in glancing angle deposition (GLAD) geometries. ZnO is employed as a compact nanocolumnar template to direct Fe growth in bilayer and multilayer architectures. Morphological analysis reveals well-defined ZnO/Fe interfaces for normal deposition geometry, with diminished interface clarity and reduced layer thickness in GLAD samples. Crystallographic characterization indicates clear ZnO-{002} and α-Fe-{110} texture. Magnetostatic characterization investigates the effects of morphology on coercivity and domain nucleation. GLAD-deposited Fe films exhibit clear in-plane magnetic anisotropy, with remanence to saturation magnetization (M_REM/M_SAT) equal to 1 for the easy axis and equal to 0.24 for the hard axis, consistent with inclined nanocolumn morphology. Our findings show that deposition geometry, rather the ZnO template, mostly affects the morphology of Fe films. The above, highlight the potential of engineered ZnO/Fe nanocomposites for magnetic, spintronic, and magnetoplasmonic applications, by tuning morphology and interface quality through deposition parameters. Full article

(This article belongs to the Section Magnetic Materials)

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23 pages, 3243 KB

Open AccessArticle

Magnetic Drug Targeting Under Pulsatile Flow: A Safety-Constrained Framework for Deposition and Retention Stability

by Sandor I. Bernad and Elena S. Bernad

Magnetochemistry 2026, 12(4), 40; https://doi.org/10.3390/magnetochemistry12040040 - 1 Apr 2026

Abstract

Magnetic drug targeting (MDT) is commonly evaluated by peak accumulation at the target site. Under pulsatile flow, however, initial deposition does not predict sustained localisation. We introduce the Magnetic Targeting Optimisation Concept (M-TOC), a safety-constrained framework that restructures MDT evaluation by separating geometric [...] Read more.

Magnetic drug targeting (MDT) is commonly evaluated by peak accumulation at the target site. Under pulsatile flow, however, initial deposition does not predict sustained localisation. We introduce the Magnetic Targeting Optimisation Concept (M-TOC), a safety-constrained framework that restructures MDT evaluation by separating geometric deposition from retention stability and embedding both within a defined hemodynamic safety window. Deposition (D) was quantified by using obstruction degree at the injection end, OD(T0), and restricted by a structural admissibility limit (OD_max = 40%). Retention stability (R) was quantified using early washout at T0 + 30 s and an apparent half-life (τ_1/2) derived from coverage decay under controlled pulsatile washout. These descriptors were integrated into a Unified Targeting Score (UTS), applied only within the admissible domain, thereby enforcing feasibility before optimisation. Three PEG-functionalised magnetoresponsive nanocluster formulations were evaluated under identical magnetic and flow conditions. D–R mapping identified distinct operating regimes and showed that no tested configuration simultaneously achieved admissible deposition and robust pulsatile stability. By formalising MDT as a constrained multi-objective problem, M-TOC provides an objective method for regime discrimination and a transferable design principle for stability-guided targeting under physiological flow. Full article

(This article belongs to the Special Issue 10th Anniversary of Magnetochemistry: Past, Present and Future)

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17 pages, 3412 KB

Open AccessArticle

Study on the Influence of Magnetic Fluid Insulation on the Sealing Performance of Upper Guide Bearing of Hydro-Generator

by Mao Liao, Zhenggui Li, Zhaoqiang Yan, Chuanjun Han, Wei Tai, Xin Chen and Yu Zheng

Magnetochemistry 2026, 12(4), 39; https://doi.org/10.3390/magnetochemistry12040039 - 25 Mar 2026

Abstract

This study focuses on the reliability issue of magnetic fluid (MF) in the magnetic fluid sealing technology for the upper guide bearing (UGB) of hydro-generators and proposes selection schemes for MF suitable for different models of hydro-generators. By analyzing the performance indicators of [...] Read more.

This study focuses on the reliability issue of magnetic fluid (MF) in the magnetic fluid sealing technology for the upper guide bearing (UGB) of hydro-generators and proposes selection schemes for MF suitable for different models of hydro-generators. By analyzing the performance indicators of five base fluids and MFs, including the acid value, flash point, oxidation stability, magnetorheological performance, breakdown voltage, dielectric loss factor and volume resistivity, the influencing factors of the insulating performance of MFs and their mechanism in sealing the UGBs of hydro-generators are investigated. The results show that, when the spindle speed is below 27 rpm, the viscosity of the MF is dominated by the magnetic field strength, while, when the speed exceeds 27 rpm, the viscosity of the MF is dominated by the shear rate. In addition, the addition of magnetic nanoparticles (MNPs) causes the breakdown voltage of the base carrier liquid to fluctuate in the range of 31.2–55.9 kV, the dielectric loss factor to fluctuate in the range of 2.5 × 10⁻⁴–6.7 × 10⁻³, and the volume resistivity to fluctuate in the range of 2.8 × 10¹¹–2.6 × 10¹² Ω·m. The research results provide a theoretical basis for the application of high-efficiency and stable magnetic fluid sealing technology. Full article

(This article belongs to the Special Issue Ferrofluids: Electromagnetic Properties and Applications)

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25 pages, 8395 KB

Open AccessArticle

Construction of a Novel Nanoparticulate Drug Co-Delivery System for Two Active Components of Traditional Chinese Medicine and Its In Vitro and In Vivo Quality Evaluation

by Siyu Wei, Gang Gui, Cancan Yuan, Ziqi Fan and Qin Xu

Magnetochemistry 2026, 12(3), 38; https://doi.org/10.3390/magnetochemistry12030038 - 19 Mar 2026

Abstract

Background: Co-delivery of two drugs with diverse physicochemical properties and a specific administration sequence holds great importance in cancer theranostics to overcome drug resistance and reduce side effects. Paclitaxel (PTX) and hydroxycamptothecin (HCPT) have long been used clinically as chemotherapeutic agents for Nasopharyn-geal [...] Read more.

Background: Co-delivery of two drugs with diverse physicochemical properties and a specific administration sequence holds great importance in cancer theranostics to overcome drug resistance and reduce side effects. Paclitaxel (PTX) and hydroxycamptothecin (HCPT) have long been used clinically as chemotherapeutic agents for Nasopharyn-geal carcinoma (NPC). However, their clinical application is severely restricted by low water solubility, poor stability, and systemic adverse reactions. Nanoparticle-based drug delivery systems provide a promising platform for combination cancer therapy. Methods: In this study, folic acid-modified and dual drug-loaded self-assembled HCPT/PTX@FA@p-PS-SPIONs were successfully fabricated via the emulsification–solvent evaporation method using amphiphilic phosphorylated polystyrene (p-PS). The characterization, cellular uptake, and in vivo pharmacokinetic profiles of the nanoparticles in NPC models were systematically investigated. Result: HCPT/PTX@FA@p-PS-SPIONs were successfully prepared with p-PS as the copolymer backbone. The nanoparticles exhibited a uniform particle size of 196.9 ± 5.5 nm and a zeta potential of −7.3 ± 0.7 mV. The encapsulation efficiency (EE) was 81.4 ± 2.5% for PTX and 67.6 ± 4.1% for HCPT. The drug loading (DL) efficiency was 18.4 ± 1.5% for PTX and 12.2 ± 1.0% for HCPT. HCPT/PTX@FA@p-PS-SPIONs showed favorable biocompatibility. Sustained and sequential release of the two drugs contributed to an enhanced therapeutic effect. Moreover, under magnetic field (MF) guidance, HCPT/PTX@FA@p-PS-SPIONs exhibited stronger inhibitory effects on NPC cells than single-drug, cocktail, or dual-drug groups, demonstrating the superiority of the combined therapy. Pharmacokinetic studies in rats revealed that the half-lives of PTX and HCPT were 3.9 ± 1.2 h and 4.7 ± 1.1 h, respectively, confirming that HCPT/PTX@FA@p-PS-SPIONs could resist rapid metabolism and clearance in vivo. Conclusions: The long-circulating, folic acid-targeted nanoparticles HCPT/PTX@FA@p-PS-SPIONs show great potential for the targeted therapy of nasopharyngeal carcinoma. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles and Nanocomposites for Biomedical Applications)

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