Magnetochemistry

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8 pages, 2098 KiB

Open AccessArticle

Comparison of Current Induced Domain Wall Motion Driven by Spin Transfer Torque and by Spin Orbit Torque in Ferrimagnetic GdFeCo Wires

by Pham Van Thach, Satoshi Sumi, Kenji Tanabe and Hiroyuki Awano

Magnetochemistry 2024, 10(5), 36; https://doi.org/10.3390/magnetochemistry10050036 - 19 May 2024

Viewed by 838

Abstract

Current-induced domain wall motion (CIDWM) in magnetic wires can be driven by spin transfer torque (STT) originating from transferring angular momentums of spin-polarized conducting electrons to the magnetic DW and can be driven by spin orbit torque (SOT) originating from the spin Hall [...] Read more.

Current-induced domain wall motion (CIDWM) in magnetic wires can be driven by spin transfer torque (STT) originating from transferring angular momentums of spin-polarized conducting electrons to the magnetic DW and can be driven by spin orbit torque (SOT) originating from the spin Hall effect (SHE) in a heavy metal layer and Dzyaloshinsky Moriya (DMI) generated at an interface between a heavy metal layer and a magnetic layer. In this work, we carried out a comparative study of CIDWM driven by STT and by SOT in ferrimagnetic GdFeCo wires with magnetic perpendicular anisotropy based on structures of SiN (10 nm)/GdFeCo (8 nm)/SiN (10 nm) and Pt (5 nm)/GdFeCo (8 nm)/SiN (10 nm). We found that CIDWM driven by SOT exhibited a much lower critical current density (J_C), and much higher DW mobility (µ_DW). Our work might be useful for the realization and the development of low-power and high-speed memory devices. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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10 pages, 2123 KiB

Open AccessArticle

Compatibility of LaFe_13−x−yMn_xSi_yH_1.6 and Eutectic Liquid GaInSn Alloy

by Jamieson Brechtl, Joseph Rendall, Mingkan Zhang, Michael R. Koehler, Kashif Nawaz and Ayyoub M. Momen

Magnetochemistry 2024, 10(2), 13; https://doi.org/10.3390/magnetochemistry10020013 - 12 Feb 2024

Viewed by 1919

Abstract

The heat transfer rate of magnetocaloric regenerators is a topic of extensive research and the cyclability of these regenerators is critical to the operation of systems with a high coefficient of performance (e.g., potentially >22, significantly higher than typical vapor compression cooling technologies). [...] Read more.

The heat transfer rate of magnetocaloric regenerators is a topic of extensive research and the cyclability of these regenerators is critical to the operation of systems with a high coefficient of performance (e.g., potentially >22, significantly higher than typical vapor compression cooling technologies). To enable a high operating frequency that will result in a high specific cooling power, the heat transfer fluid should have high thermal conductivity and lower specific heat, i.e., higher thermal diffusivity. Eutectic metal alloys possess these qualities, such as gallium–indium–tin (Galinstan), whose thermal diffusivity has been found to be approximately an order of magnitude higher than water. For this study, the effects of eutectic liquid Galinstan exposure on the phase stability of LaFe_13−x−yMn_xSi_yH_1.6 magnetocaloric powders in an active magnetic regenerator device were investigated. The powders were characterized before and after exposure to Galinstan using X-ray diffraction, in which the phases were determined using the Rietveld refinement technique and X-ray fluorescence. It was found that after Galinstan exposure, hydrogen containing phases were present in the powder, suggesting that the hydrogen was lost from the magnetocaloric phase. The magnetocaloric phase degradation indicates that the powder was incompatible with the Galinstan metal in an environment with moisture. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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24 pages, 16841 KiB

Open AccessEditor’s ChoiceArticle

On the Magnetization and Entanglement Plateaus in One-Dimensional Confined Molecular Magnets

by Javier I. Norambuena Leiva, Emilio A. Cortés Estay, Eric Suarez Morell and Juan M. Florez

Magnetochemistry 2024, 10(2), 10; https://doi.org/10.3390/magnetochemistry10020010 - 1 Feb 2024

Viewed by 1597

Abstract

One-dimensional (1D) magnetic systems offer rich phenomena in the quantum limit, proving more chemically accessible than zero-dimensional or higher-dimensional frameworks. Single-walled carbon nanotubes (SWCNT) have recently been used to encapsulate trimetric nickel(II) acetylacetonate [Nanoscale, 2019, 11, 10615–10621]. Here, we investigate the magnetization on [...] Read more.

One-dimensional (1D) magnetic systems offer rich phenomena in the quantum limit, proving more chemically accessible than zero-dimensional or higher-dimensional frameworks. Single-walled carbon nanotubes (SWCNT) have recently been used to encapsulate trimetric nickel(II) acetylacetonate [Nanoscale, 2019, 11, 10615–10621]. Here, we investigate the magnetization on spin chains based on nickel trimers by Matrix Product State (MPS) simulations. Our findings reveal plateaus in the exchange/magnetic-field phase diagram for three coupling configurations, showcasing effective dimeric and trimeric spin-ordering with similar or staggered entanglement across chains. These ordered states allow the qubit-like tuning of specific local magnetic moments, exhibiting disengagement or uniform coupling in entanglement plateaus. This behavior is consistent with the experimental transition from frustrated (3D) to non-frustrated (1D) molecules, corresponding to large and smaller SWCNT diameters. Our study offers insights into the potential of 1D-confined trimers for quantum computation, extending beyond the confinement of trimetric nickel-based molecules in one dimension. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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13 pages, 3035 KiB

Open AccessArticle

The Magnetostriction of Amorphous Magnetic Microwires: The Role of the Local Atomic Environment and Internal Stresses Relaxation

by Valentina Zhukova, Alfonso García-Gómez, Alvaro Gonzalez, Margarita Churyukanova, Sergey Kaloshkin, Paula Corte-Leon, Mihail Ipatov, Jesus Olivera and Arcady Zhukov

Magnetochemistry 2023, 9(10), 222; https://doi.org/10.3390/magnetochemistry9100222 - 20 Oct 2023

Cited by 2 | Viewed by 1642

Abstract

We studied the magnetostriction coefficients, λ_s, Curie temperature, T_c, and their dependence on annealing conditions in Fe₄₇Ni₂₇Si₁₁B₁₃C₂ and Co₆₇Fe_3.9Ni₁.₅B₁₁.₅ [...] Read more.

We studied the magnetostriction coefficients, λ_s, Curie temperature, T_c, and their dependence on annealing conditions in Fe₄₇Ni₂₇Si₁₁B₁₃C₂ and Co₆₇Fe_3.9Ni₁.₅B₁₁.₅Si_14.5Mo_1.6 amorphous glass-coated microwires with rather different character of hysteresis loops. A positive λ_s ≈ 20 × 10⁻⁶ is observed in as-prepared Fe₄₇Ni₂₇Si₁₁B₁₃C_2, while low and negative λ_s ≈ −0.3 × 10⁻⁶ is obtained for Co₆₇Fe_3.9Ni₁.₅B₁₁.₅Si_14.5Mo_1.6 microwire. Annealing affects the magnetostriction coefficients and Curie temperatures, T_c, of both Fe₄₇Ni₂₇Si₁₁B₁₃C₂ and Co₆₇Fe_3.9Ni₁.₅B₁₁.₅Si_14.5Mo_1.6 glass-coated microwires in a similar way. Observed dependencies of hysteresis loops, λ_s and T_c on annealing conditions are discussed in terms of superposition of internal stresses relaxation and structural relaxation of studied microwires. We observed linear λ_s dependence on applied stress, σ, in both studied microwires. A decrease in the magnetostriction coefficient upon applied stress is observed for Co-rich microwires with low and negative magnetostriction coefficient. On the contrary, for Fe-Ni-rich microwires with a positive magnetostriction coefficient, an increase in the magnetostriction coefficient with applied stress is observed. The observed results are discussed considering the internal stresses relaxation and short range atomic rearrangements induced by annealing on hysteresis loops, magnetostriction coefficients and Curie temperatures of studied microwires. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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14 pages, 3303 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of the Particle Size on the Electrical, Magnetic and Biological Properties of the Bioglass^® Containing Iron Oxide

by Joana Soares Regadas, Sílvia Rodrigues Gavinho, Sílvia Soreto Teixeira, Juliana Vieira de Jesus, Ana Sofia Pádua, Jorge Carvalho Silva, Susana Devesa and Manuel Pedro Fernandes Graça

Magnetochemistry 2023, 9(9), 209; https://doi.org/10.3390/magnetochemistry9090209 - 12 Sep 2023

Viewed by 1632

Abstract

Bioglasses have been used throughout the past century as a biomaterial in the bone regeneration field. However, recent studies have attempted to use them as a therapeutic material as well, mainly in the treatment of osteosarcomas. The most widely recognized bioglass is the [...] Read more.

Bioglasses have been used throughout the past century as a biomaterial in the bone regeneration field. However, recent studies have attempted to use them as a therapeutic material as well, mainly in the treatment of osteosarcomas. The most widely recognized bioglass is the 45S5 Bioglass, invented by Larry Hench et al., which presents higher bioactivity. A possible application of this bioglass in the treatment of osteosarcomas can be accomplished by adding specific ions, such as iron, that will allow the use of magnetic hyperthermia and Fenton reaction as therapeutic mechanisms. In this study, a 45S5 Bioglass containing 10%mol of Fe₂O₃ was produced using the melt-quenching method. A group of samples was prepared by changing the overall ball milling time, from 1 h up to 48 h, to analyze the effects of iron in the bioactive glass matrix and evaluate the influence of particle size on their physical and biological properties. The studied bioglasses showed no evidence of changes in the amorphous structural nature compared to the 45S5 Bioglass. The data of the impedance spectroscopy study revealed that the addition of Fe₂O₃ can increase the standard rate constant of the Electro-Fenton reaction, with the sample milled for 12 h showing the most promising results. The reduction in the particle size influenced the cytotoxicity and the bioactivity. The samples with lower particle sizes showed a higher level of cytotoxicity. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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25 pages, 8960 KiB

Open AccessFeature PaperArticle

NiFe Alloy Nanoparticles Tuning the Structure, Magnetism, and Application for Oxygen Evolution Reaction Catalysis

by Rafael A. Raimundo, Vinícius D. Silva, Luciena S. Ferreira, Francisco J. A. Loureiro, Duncan P. Fagg, Daniel A. Macedo, Uílame U. Gomes, Márcio M. Soares, Rodinei M. Gomes and Marco A. Morales

Magnetochemistry 2023, 9(8), 201; https://doi.org/10.3390/magnetochemistry9080201 - 8 Aug 2023

Cited by 4 | Viewed by 2414

Abstract

In this study, Ni-Fe alloy nanoparticles were prepared using the proteic sol–gel method, followed by a reduction in H₂ at 500 and 700 °C, namely hereafter as NiFe-500 and NiFe-700, respectively. The morphological, structural, and magnetic properties were tuned via the thermal [...] Read more.

In this study, Ni-Fe alloy nanoparticles were prepared using the proteic sol–gel method, followed by a reduction in H₂ at 500 and 700 °C, namely hereafter as NiFe-500 and NiFe-700, respectively. The morphological, structural, and magnetic properties were tuned via the thermal treatment in H₂. The samples were studied using XPS, TEM, Mössbauer spectroscopy, DC magnetic measurements, and electrochemical measurements. Ritveld refinements showed that the sample NiFe-500 has FCC (face-centered cubic) and BCC (body-centered cubic) NiFe alloys, while the sample NiFe-700 has only FCC NiFe alloy. For both samples, magnetization measurements in the range of 300–900 K showed the presence of the Griffiths phase, indicating the formation of clusters of either Fe or Ni-Fe alloys rich in Fe. The sample NiFe-500 presented ferromagnetic (FM) transitions at 533, 700, and 834 K, assigned to the alloys Ni₃₇Fe₆₃-FCC, Ni₄₆Fe₅₄-FCC, and Ni₅₅Fe₄₅-FCC, respectively. In contrast, we could not observe the FM transition of the BCC Ni-Fe alloy because of limitations in our experimental setup (T ≤ 900 K). Meanwhile, three FM transitions were observed for the sample NiFe-700 at 480, 655, and 825 K, attributed to the alloys Ni₃₄Fe₆₆-FCC, Ni₄₃Fe₅₇-FCC, and Ni₅₄Fe₄₆-FCC, respectively. At 5 K, the samples NiFe-500 and NiFe-700 have saturation magnetizations of 164.2 and 173.6 emu g⁻¹, respectively. For application in Oxygen Evolution Reaction catalysis, the samples NiFe-500 and NiFe-700 showed different overpotentials of 319 and 307 mV at 10 mA cm⁻². These low overpotential values indicate a higher electrochemical activity of the FCC Ni-Fe alloy and, for both samples, a superior electrocatalytic activity in comparison to RuO₂ e IrO₂ conventional catalysts. Furthermore, the samples showed high electrochemical stability in chrono potentiometric studies for up to 15 h. This current work highlights that the Ni-Fe alloys produced via the proteic sol–gel and with a reduction in H₂ methods can be promising for OER systems due to their good performance and low costs. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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16 pages, 5462 KiB

Open AccessArticle

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Bulk Manganites La_0.7Ba_(0.3−x)Ca_xMnO₃ (x ≤ 0.25)

by Roman Atanasov, Ecaterina Brinza, Rares Bortnic, Razvan Hirian, Gabriela Souca, Lucian Barbu-Tudoran and Iosif Grigore Deac

Magnetochemistry 2023, 9(7), 170; https://doi.org/10.3390/magnetochemistry9070170 - 30 Jun 2023

Cited by 3 | Viewed by 1461

Abstract

Here we report the synthesis and investigation of bulk and nano-sized La_0.7Ba_0.3−xCa_xMnO₃ (x = 0, 0.15, 0.2 and 0.25) compounds that are promising candidates for magnetic refrigeration applications. We compare the structural and magnetic properties of [...] Read more.

Here we report the synthesis and investigation of bulk and nano-sized La_0.7Ba_0.3−xCa_xMnO₃ (x = 0, 0.15, 0.2 and 0.25) compounds that are promising candidates for magnetic refrigeration applications. We compare the structural and magnetic properties of bulk and nano-scale polycrystalline La_0.7Ba_0.3−xCa_xMnO₃ for potential use in magnetic cooling systems. Solid-state reactions were implemented for bulk materials, while the sol–gel method was used for nano-sized particles. Structurally and morphologically, the samples were investigated by X-ray diffraction (XRD), optical microscopy and transmission electron microscopy (TEM). Oxygen stoichiometry was investigated by iodometry. Bulk compounds exhibit oxygen deficiency, while nano-sized particles show excess oxygen. Critical magnetic behavior was revealed for all samples using the modified Arrott plot (MAP) method and confirmed by the Kouvel–Fisher (KF) method. The bulk polycrystalline compound behavior was better described by the tricritical field model, while the nanocrystalline samples were governed by the mean-field model. Resistivity in bulk material showed a peak at a temperature T_p1 attributed to grain boundary conditions and at T_p2 associated with a Curie temperature of T_c_. Parent polycrystalline sample La_0.7Ba_0.3MnO₃ has T_c at 340 K. Substitution of x = 0.15 of Ca brings T_c to 308 K, and x = 0.2 brings it to 279 K. Nanocrystalline samples exhibit a very wide effective temperature range in the magnetocaloric effect, up to 100 K. Bulk compounds exhibit a high and sharp peak in magnetic entropy change, up to 7 J/kgK at 4 T at T_c for x = 0.25. To compare the magnetocaloric performances of the studied compounds, both relative cooling power (RCP) and temperature-averaged entropy change (TEC) figures of merit were used. RCP is comparable for bulk polycrystalline and nano-sized samples of the same substitution level, while TEC shows a large difference between the two systems. The combination of bulk and nanocrystalline materials can contribute to the effectiveness and improvement of magnetocaloric materials. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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12 pages, 3876 KiB

Open AccessArticle

Structural and Magnetic Investigations of the Novel Pyrophosphate Na₇Ni₃Fe(P₂O₇)₄

by Sirine El Arni, Mohammed Hadouchi, Abderrazzak Assani, Mohamed Saadi, Mimoun El Marssi, Abdelilah Lahmar and Lahcen El Ammari

Magnetochemistry 2023, 9(7), 162; https://doi.org/10.3390/magnetochemistry9070162 - 24 Jun 2023

Cited by 3 | Viewed by 1403

Abstract

A novel pyrophosphate Na₇Ni₃Fe(P₂O₇)₄ was synthesized in two distinct forms, single-crystal and powder. Single-crystal X-ray diffraction was used to determine the crystal structure, and powder X-ray diffraction and scanning electron microscopy were used to [...] Read more.

A novel pyrophosphate Na₇Ni₃Fe(P₂O₇)₄ was synthesized in two distinct forms, single-crystal and powder. Single-crystal X-ray diffraction was used to determine the crystal structure, and powder X-ray diffraction and scanning electron microscopy were used to examine the purity and morphology of the elaborated powder. This phosphate crystallizes in the P

\bar{1}

space group of the triclinic system with a = 6.3677 (2) Å, b = 9.3316 (4) Å, c = 10.8478 (4) Å, α = 65.191 (1)°, β = 80.533 (1)° and γ = 73.042 (1)°. The crystal framework is assembled from the linkage of centro-symmetrical clusters Ni₂(Ni/Fe)₂P₄O₂₈. Each cluster consists of two (Fe1/Ni1)O₆ octahedra, two Ni2O₆ octahedra and two P₂O₇ units. The linkage of these clusters is provided by two other P₂O₇ units to generate a three-dimensional structure with distinct tunnels in the [100], [010] and [001] directions, housing the Na⁺ cations. The infrared and Raman analyses show the characteristic bands of the pyrophosphate anion P₂O₇⁴⁻. Remarkably, the magnetic investigations revealed the coexistence of two magnetic transitions at ~29 K and ~4.5 K with dominating antiferromagnetic interactions. Full article

(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)

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