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Magnetochemistry, Volume 11, Issue 2 (February 2025) – 13 articles

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13 pages, 3178 KiB  
Article
Failure Mechanisms of Ester-Based Magnetic Fluid Seals at High Speeds: Thermal Dissipation and Fluid Loss
by Jixian Yang, Decai Li and Licong Jin
Magnetochemistry 2025, 11(2), 18; https://doi.org/10.3390/magnetochemistry11020018 - 18 Feb 2025
Viewed by 568
Abstract
Magnetic fluid seals are well known for their zero-leakage performance but are limited at high rotational speeds due to heat generation and fluid loss. This study experimentally investigates the failure mechanisms of ester-based magnetic fluid seals at high speeds, specifically focusing on thermal [...] Read more.
Magnetic fluid seals are well known for their zero-leakage performance but are limited at high rotational speeds due to heat generation and fluid loss. This study experimentally investigates the failure mechanisms of ester-based magnetic fluid seals at high speeds, specifically focusing on thermal dissipation and fluid loss. A custom-designed high-speed rotary seal test platform was developed, and experimental studies were conducted to evaluate sealing performance. Our results showed significant temperature increases and fluid loss at higher rotational speeds, with a noticeable fluid ejection phenomenon occurring at approximately 13.7 m/s, and the sealing gap temperature reached 92 °C at 9000 rpm under uncooled conditions. This study experimentally verified that the main failure mechanisms of magnetic fluid seals at high speeds are centrifugal force and thermal dissipation, and proposed future design directions. This research provides key insights into the failure of high-speed magnetic fluid seals and offers a potential approach for improved high-speed sealing performance. Full article
(This article belongs to the Special Issue Ferrofluids: Electromagnetic Properties and Applications)
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13 pages, 3859 KiB  
Article
Design of a 2–4 Decoder Based on All-Spin Logic and Magnetic Tunnel Junction
by Sen Wang, Yongfeng Zhang and Dan Shan
Magnetochemistry 2025, 11(2), 17; https://doi.org/10.3390/magnetochemistry11020017 - 15 Feb 2025
Viewed by 475
Abstract
A 2–4 decoder based on all-spin logic (ASL) and magnetic tunnel junction (MTJ) is proposed. The decoder employs five-input minority gates to realize three-input NOR gates, which reduces the circuit size compared to the three-input minority gates. Simultaneously, the inputs of the original [...] Read more.
A 2–4 decoder based on all-spin logic (ASL) and magnetic tunnel junction (MTJ) is proposed. The decoder employs five-input minority gates to realize three-input NOR gates, which reduces the circuit size compared to the three-input minority gates. Simultaneously, the inputs of the original and reverse variables are implemented by initializing the MTJ fixed layer magnetization in different directions, which avoids the use of inverters. In addition, the 2–4 decoder adopts a single-input single-fan-out (SISF) structure, which reduces the channel length. To illustrate the advantages of the five-input minority gate, inverter-free structure, and SISF structures in designing the proposed 2–4 decoder, a second 2–4 decoder is proposed that uses three-input minority gates, inverters, and a single-input multiple-fan-out structure. Compared with the second decoder, the first decoder has the layout area reduced to 37.9%, the total channel length reduced to 40.8%, and the number of clock cycles reduced to one-third. Importantly, the design methods used in this work, such as multi-input minority gates, SISF structure, and inverter-free structure, provide an interesting approach for designing large-scale ASL logic circuits. Full article
(This article belongs to the Special Issue Design and Application of Spintronic Devices)
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14 pages, 5032 KiB  
Article
Er(III) and Yb(III) Complexes with a Tripodal Nitroxyl Radical: Magnetochemical Study and Ab Initio Calculations
by Mauro Perfetti, Alexey A. Dmitriev and Kira E. Vostrikova
Magnetochemistry 2025, 11(2), 16; https://doi.org/10.3390/magnetochemistry11020016 - 14 Feb 2025
Viewed by 570
Abstract
In this paper, we investigate the magnetic exchange interaction and magnetization dynamics of two new members of the [LnRad(NO3)3] family, where Rad is a tripodal nitroxide, and Ln is Er(III) or Yb(III), having the prolate type electron density. Single [...] Read more.
In this paper, we investigate the magnetic exchange interaction and magnetization dynamics of two new members of the [LnRad(NO3)3] family, where Rad is a tripodal nitroxide, and Ln is Er(III) or Yb(III), having the prolate type electron density. Single OK crystal and powder X-ray diffraction studies showed that these complexes are isostructural with their previously investigated Y, Gd, Dy, Tm, Tb, Eu, and Lu congeners. A magnetometric investigation, supported by ab initio calculations, showed the presence of antiferromagnetic coupling between the lanthanide ion and the radical in both compounds with estimated J values of ≈7 and ≈20 cm−1 for Er and Yb, respectively (+J SeffS formalism). Full article
(This article belongs to the Special Issue Latest Research on the Magnetic Properties of Coordination Compounds)
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1 pages, 135 KiB  
Correction
Correction: Atalay et al. Fabrication of a Portable Magnetic Microcantilever Using Fe40Ni38Mo4B18 Amorphous Ribbon and Its Application as a Humidity Sensor by Coating with TiO2 Nanotubes. Magnetochemistry 2024, 10, 98
by Selçuk Atalay, Sema Erdemoglu, Hatice Çağlar Yılmaz, Emine Mete, Orhan Orcun Inan and Veli Serkan Kolat
Magnetochemistry 2025, 11(2), 15; https://doi.org/10.3390/magnetochemistry11020015 - 13 Feb 2025
Viewed by 286
Abstract
In the original publication [...] Full article
21 pages, 9468 KiB  
Article
Development and Evaluation of Magnetite Loaded Alginate Beads Based Nanocomposite for Enhanced Targeted Analgesic Drug Delivery
by Amrita Das, Prateep Sengupta, Shreya Chatterjee, Jasmina Khanam, Pranab Kumar Mondal, Eder Lilia Romero, Anton M. Manakhov, Sabu Thomas, Syed Mahmood and Kajal Ghosal
Magnetochemistry 2025, 11(2), 14; https://doi.org/10.3390/magnetochemistry11020014 - 13 Feb 2025
Viewed by 921
Abstract
Iron oxide-based nanoparticles, such as magnetic nanoparticles (MNPs), have gained significant attention in the area of drug delivery due to their unique magnetic properties, allowing for precise targeting and controlled release of therapeutic agents. Several successful research studies were reported with combinations of [...] Read more.
Iron oxide-based nanoparticles, such as magnetic nanoparticles (MNPs), have gained significant attention in the area of drug delivery due to their unique magnetic properties, allowing for precise targeting and controlled release of therapeutic agents. Several successful research studies were reported with combinations of magnetic nanoparticles and polysaccharides such as sodium alginate, chitosan, cellulose, etc. The presented research work is based on synthesising MNPs via the co-precipitation method and their successful encapsulation within alginate beads, serving as a promising drug delivery system for aceclofenac, a model drug. The physical and chemical characteristics of both the prepared magnetite nanoparticles and the aceclofenac-loaded MNPs alginate beads were thoroughly examined using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and vibrating sample magnetometry (VSM). Furthermore, a drug release study was conducted to evaluate the release kinetics of aceclofenac from the prepared MNP alginate beads. The magnetic characteristics of magnetite and MNP beads shed light on the potential application of novel drug delivery systems for magnetically targeted therapeutic interventions. The present research offers valuable insights into the development of magnetic nanoparticle-based drug carriers, paving the way for enhanced drug delivery strategies in the field of pharmaceutical sciences. Full article
(This article belongs to the Section Applications of Magnetism and Magnetic Materials)
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20 pages, 7497 KiB  
Article
Synthesis of Magnetic Nanoparticles Coated with Human Serum Albumin and Loaded by Doxorubicin
by Kirill Petrov, Elena Ryabova, Elena Dmitrienko and Alexey Chubarov
Magnetochemistry 2025, 11(2), 13; https://doi.org/10.3390/magnetochemistry11020013 - 13 Feb 2025
Viewed by 858
Abstract
Magnetic iron oxide (II,III) nanoparticles (MNPs) are highly interested in biomedicine. However, their application is limited by oxidation, aggregation, rapid clearance from the body, and poor biodistribution. Coating by human serum albumin (HSA), the predominant blood plasma protein, can significantly influence properties, prolong [...] Read more.
Magnetic iron oxide (II,III) nanoparticles (MNPs) are highly interested in biomedicine. However, their application is limited by oxidation, aggregation, rapid clearance from the body, and poor biodistribution. Coating by human serum albumin (HSA), the predominant blood plasma protein, can significantly influence properties, prolong circulation half-life, and enhance tumor capture efficiency. Here, we report the synthesis of oleic acid and Tween20-coated MNPs and their interaction with HSA. The influence of albumin coating on MNP size, zeta potential, aggregation ability, and toxicity was studied. The particles were characterized by dynamic light scattering, transmission electron microscopy, and Fourier transform infrared spectroscopy methods. The nanoparticles’ relaxivities (r1 and r2) were assessed under a magnetic field of 1.88 T to evaluate their performance in MRI applications. The anticancer drug doxorubicin (DOX) loading capacity of up to 725 µg/mg for albumin-coated MNPs was determined. DOX-loaded MNPs displayed pH-sensitive drug release during acidic conditions. The series of DOX-loaded nanocomposites indicated inhibition of A549 cell lines, and the IC50 values were evaluated. This research underscores the utility of HSA-coated MNPs in enhancing the efficacy and stability of drug delivery systems in biomedicine. Full article
(This article belongs to the Special Issue Fundamentals and Applications of Novel Functional Magnetic Materials)
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12 pages, 5695 KiB  
Article
An Organic–Inorganic Hybrid Semiconducting Quantum Spin Liquid Candidate: (BEDT-TTF)3[Cu2(μ-C2O4)3·CH3CH2OH·1.2H2O]
by Bin Zhang, Yan Zhang, Dongwei Wang, Zheming Wang, Guangcai Chang, Zengqiang Gao, Yanjun Guo, Fen Liu, Zhijuan Zhao, Xiaoyu Zhang, Baolong Qu, Peng Xu, Jiaou Wang, Fenliang Dong, Tongling Liang, Yang Sun, Deliang Yang, Qiaolian Li, Xiaofei Luo, Rongjuan Feng, Mei Liu and Xueying Zhangadd Show full author list remove Hide full author list
Magnetochemistry 2025, 11(2), 12; https://doi.org/10.3390/magnetochemistry11020012 - 12 Feb 2025
Viewed by 703
Abstract
The organic–inorganic hybrid (BEDT-TTF)3[Cu2(μ-C2O4)3·CH3CH2OH·1.2H2O] (I) was obtained using the electrocrystallization method. It comprises a θ21-phase organic donor layer and a two-dimensional inorganic antiferromagnetic [...] Read more.
The organic–inorganic hybrid (BEDT-TTF)3[Cu2(μ-C2O4)3·CH3CH2OH·1.2H2O] (I) was obtained using the electrocrystallization method. It comprises a θ21-phase organic donor layer and a two-dimensional inorganic antiferromagnetic honeycomb lattice. Cu(II) is octahedrally coordinated by three bisbidenetate oxalates, exhibiting Jahn–Teller distortion. CH3CH2OH and H2O molecules are located within the cavities of the honeycomb lattice. The total formal charge of the three donor molecules was assigned to be +2 based on the bond lengths in the TTF core, which corresponded to the Raman spectra. It is a semiconductor with σrt = 0.04 S/cm and Eα = 40 meV. No long-range ordering was observed above 2 K from zero-field cooling/field cooling magnetization, as confirmed by specific heat measurements. The spin frustration with f > 10 from the antiferromagnetic copper-oxalate-framework was observed. It is a candidate quantum spin liquid. Full article
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11 pages, 10123 KiB  
Article
Magnetic Anisotropy and Slow Magnetic Relaxation in Two Mononuclear Octahedral Cobalt(II) Complexes
by Hui-Hui Cui, Dou-Zun Wang, Shixiang Li, Leixin Wang, Xinrui Yu, Xiancong Liu, Jin Wang, Miao Wang and Yanfeng Tang
Magnetochemistry 2025, 11(2), 11; https://doi.org/10.3390/magnetochemistry11020011 - 11 Feb 2025
Viewed by 568
Abstract
Two mononuclear octahedral Co(II) complexes, [Co(L)X2] (L = 1-(prop-2-en-1-yl)-1H-imidazole, X = NCS (1) and NCSe (2)), have been synthesized and characterized. The central Co(II) ions in two complexes adopt an octahedral geometry, coordinated [...] Read more.
Two mononuclear octahedral Co(II) complexes, [Co(L)X2] (L = 1-(prop-2-en-1-yl)-1H-imidazole, X = NCS (1) and NCSe (2)), have been synthesized and characterized. The central Co(II) ions in two complexes adopt an octahedral geometry, coordinated by four N atoms from the ligand and two N atoms from the anion. Direct-current magnetic data revealed large easy-plane magnetic anisotropy in both 1 and 2. Dynamic magnetic measurements demonstrated that 1 and 2 display field-induced slow magnetic relaxation. For 1 and 2, the Raman mechanism is found to the dominant process in the whole temperature range. Compared to 1, the magnetic relaxation of 2 is faster, likely due to the presence of the hydrogen bonding system in 2. Full article
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11 pages, 2452 KiB  
Article
Positive and Negative Exchange Bias in N-, P- and Q-Type Ferri-Magnets of Niccolite Metal Formates [CH3NH2CH3]n[CrIII1−xFeIIIxFeII(HCO2)6]n
by Yu Zhou, Zhaoquan Yao, Na Li, Fuchen Liu, Jiongpeng Zhao and Xianhe Bu
Magnetochemistry 2025, 11(2), 10; https://doi.org/10.3390/magnetochemistry11020010 - 11 Feb 2025
Viewed by 531
Abstract
Exchange bias (EB) materials, whose magnetization curve can shift along the field axis after field cooling, have attracted tremendous attention and play a crucial role in the development of fundamental physics as well as practical applications of magnetization storage. In this work, the [...] Read more.
Exchange bias (EB) materials, whose magnetization curve can shift along the field axis after field cooling, have attracted tremendous attention and play a crucial role in the development of fundamental physics as well as practical applications of magnetization storage. In this work, the N-, P-, and Q-type ferrimagnets of Néel’s notation were realized in mixed valence metal formates [CH3NH2CH3]n[CrIII1−xFeIIIxFeII(HCO2)6]n by altering x, respectively. The positive and negative EB was found in N- and P-type ferrimagnets. The exchange anisotropy originates from the antiferromagnetic exchange interaction between the uncompensated spin of the host ferrimagnetic lattice and the pinned compensated spin of the antiferromagnetic clusters as a guest, which is rooted in the valence disorder of the iron ions. Full article
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44 pages, 2672 KiB  
Review
Magnetic Nanoparticles: Advances in Synthesis, Sensing, and Theragnostic Applications
by Adeyemi O. Adeeyo, Mercy A. Alabi, Joshua A. Oyetade, Thabo T. I. Nkambule, Bhekie B. Mamba, Adewale O. Oladipo, Rachel Makungo and Titus A. M. Msagati
Magnetochemistry 2025, 11(2), 9; https://doi.org/10.3390/magnetochemistry11020009 - 26 Jan 2025
Viewed by 1878
Abstract
The synthesis of magnetic nanoparticles (MNPs) via the chemical, biological, and physical routes has been reported on along with advantages and attendant limitations. This study focuses on the sensing and emerging theragnostic applications of this category of nanoparticles (NPs) in clinical sciences by [...] Read more.
The synthesis of magnetic nanoparticles (MNPs) via the chemical, biological, and physical routes has been reported on along with advantages and attendant limitations. This study focuses on the sensing and emerging theragnostic applications of this category of nanoparticles (NPs) in clinical sciences by unveiling the unique performance of these NPs in the biological sensing of bacteria and nucleotide sequencing. Also, in terms of medicine and clinical science, this review analyzes the emerging theragnostic applications of NPs in drug delivery, bone tissue engineering, deep brain stimulation, therapeutic hyperthermia, tumor detection, magnetic imaging and cell tracking, lymph node visualization, blood purification, and COVID-19 detection. This review presents succinct surface functionalization and unique surface coating techniques to confer less toxicity and biocompatibility during synthesis, which are often identified as limitations in medical applications. This study also indicates that these surface improvement techniques are useful for refining the selective activity of MNPs during their use as sensors and biomarkers. In addition, this study unveils attendant limitations, especially toxicological impacts on biomolecules, and suggests that future research should pay attention to the mitigation of the biotoxicity of MNPs. Thus, this study presents a proficient approach for the synthesis of high-performance MNPs fit for proficient medicine in the detection of microorganisms, better diagnosis, and treatment in medicine. Full article
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15 pages, 3433 KiB  
Article
Comprehensively Understanding the Transformation of Paramagnetic Tetramer to Spin-Paired Dimer in an S = ½ Molecular Crystal
by Yin Qian, Yan Gao, Lei Xu, Reinhard K. Kremer, Jin Zhang and Xiao-Ming Ren
Magnetochemistry 2025, 11(2), 8; https://doi.org/10.3390/magnetochemistry11020008 - 24 Jan 2025
Viewed by 918
Abstract
In this study, we comparatively analyzed the variable-temperature crystal structures for two isomorphous salts, [1-benzyl-4-aminopyridinium][M(mnt)2] (M = Ni or Cu; mnt2− = maleonitriledithiolate; labeled as APy-Ni or APy-Cu). Both salts crystallize in the triclinic P–1 space group at [...] Read more.
In this study, we comparatively analyzed the variable-temperature crystal structures for two isomorphous salts, [1-benzyl-4-aminopyridinium][M(mnt)2] (M = Ni or Cu; mnt2− = maleonitriledithiolate; labeled as APy-Ni or APy-Cu). Both salts crystallize in the triclinic P–1 space group at 296 K, comprising linear [M(mnt)2] (M = Ni or Cu) tetramers. A magnetostructural phase transition occurs at TC~190 K in S = ½ APy-Ni at ambient pressure, with a conversion of paramagnetic tetramers into nonmagnetic spin-paired dimers. The discontinuous alteration of cell parameters at TC signifies the characteristic of first-order phase transition in APy-Ni. No such transition appears in the nonmagnetic APy-Cu within the same temperature vicinity, demonstrating the magnetic interactions promoting the structural phase transition in APy-Ni, which is further reinforced through a comparison of the lattice formation energy between APy-Ni and APy-Cu. The phase transition may bear a resemblance to the mechanisms typically observed in spin-Peierls systems. We further explored the magnetic and phase transition properties of APy-Ni under varying pressures. Significantly, TC shows a linear increase with rising pressure within the range of 0.003–0.88 GPa, with a rate of 90 K GPa−1, manifesting that the applied pressure promotes the transition from tetramer to dimer. Full article
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10 pages, 2792 KiB  
Article
Enhancement of Spin Wave Transmission Through Antiferromagnet in Pt/NiO/CoFeB Heterostructure
by Wei Shi, Yangkai Wang, Zhixin Liu, Yilin Pei, Qiuping Huang, Zhengping Fu, Jianlin Wang and Yalin Lu
Magnetochemistry 2025, 11(2), 7; https://doi.org/10.3390/magnetochemistry11020007 - 22 Jan 2025
Viewed by 1065
Abstract
A significant enhancement of the spin current transmission through the antiferromagnetic insulating material NiO in Pt/NiO/CoFeB heterostructures was observed in this work. The ultrafast spin currents excited by laser pulses were injected into the Pt layers after passing through the NiO layers, and [...] Read more.
A significant enhancement of the spin current transmission through the antiferromagnetic insulating material NiO in Pt/NiO/CoFeB heterostructures was observed in this work. The ultrafast spin currents excited by laser pulses were injected into the Pt layers after passing through the NiO layers, and then transient charge currents were generated via the inverse spin Hall effect (ISHE), leading to a terahertz (THz) emission from the structure. The emitted THz signals were measured using electro-optic sampling with a ZnTe crystal. Thin NiO layers remarkably enhanced the THz signal amplitude, suggesting high spin transfer efficiency in NiO, and lighting a direction to ameliorate the spintronic THz emitter. The variable temperature measurements showed the amplitude had a maximum near the Néel temperature (TN) of the NiO layer with a specific thickness. The results of phase difference suggested that the coherent evanescent spin wave-mediated transmission had a contribution below the TN of the NiO layer, while the thermal magnon-mediated transmission existed at all temperatures. Our results not only achieve an enhancement in the spintronic THz source but also provide a THz spectroscopic method to investigate the dynamics of the ultrafast spintronic phenomenon. Full article
(This article belongs to the Special Issue Spin Waves in Magnonic Crystals and Hybrid Ferromagnetic Structures)
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38 pages, 16698 KiB  
Article
Laudatio: Miguel Julve and Francisco Lloret, a Friendly Pair of Two Exceptional Coordination Chemists in Molecular Magnetism
by Michel Verdaguer
Magnetochemistry 2025, 11(2), 6; https://doi.org/10.3390/magnetochemistry11020006 - 21 Jan 2025
Viewed by 1149
Abstract
This laudatio is dedicated to Professors Miguel Julve Olcina and Francisco Lloret Pastor on the occasion of their retirement in 2024. The first part deals with the scientific trajectory of the Coordination Chemistry team at the University of Valencia, within the Department of [...] Read more.
This laudatio is dedicated to Professors Miguel Julve Olcina and Francisco Lloret Pastor on the occasion of their retirement in 2024. The first part deals with the scientific trajectory of the Coordination Chemistry team at the University of Valencia, within the Department of Inorganic Chemistry on the Burjassot campus and then in the Paterna Institute of Molecular Science. The second part relates some of the more salient results of the heritage left by our two colleagues in molecular magnetism, where they developed, in their own way, a rational approach to designing, creating and understanding a wealth of brand new systems from the simplest to Multifunctional Molecule-based Magnetic Materials. The robust and friendly links between our two colleagues are emphasized in the third part. Full article
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