Article
Engineering, Electrical & Electronic
Frederic Mazaleyrat
Summary: This article discusses the importance of hard magnets in transportation technologies and renewable energies. It highlights the anticipated high demand for magnets in the automobile industry as it switches to full electric drive in the next 30 years. However, the reliance on critical materials, such as rare-earth elements and cobalt, poses a potential market challenge. The article reviews existing hard magnets with functional properties suitable for automobile electric drives and explores the evolution of materials aiming to reduce or eliminate the use of critical elements.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Chemistry, Physical
Jeotikanta Mohapatra, Xubo Liu, Pramanand Joshi, J. Ping Liu
Summary: Iron (Fe) is an important ferromagnetic element with high magnetic moment and Curie temperature, and it is widely used in technologies and industries. While Fe-based materials are mostly used as soft magnetic materials due to low magneto-crystalline anisotropy (MCA), recent research has shown promising evidence for achieving high MCA in Fe-based hard magnetic materials without rare-earth elements. This paper reviews the history and recent developments of Fe-based hard and semi-hard magnetic materials, focusing on the mechanisms of high MCA and the related crystal and electronic structures.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Review
Materials Science, Multidisciplinary
Jeotikanta Mohapatra, Pramanand Joshi, J. Ping Liu
Summary: When ferromagnetic materials reduce their size to the nanometer scale, their magnetic ordering and properties change due to size-sensitive physical phenomena. This review discusses the scientific and technological problems of low-dimensional ferromagnetic materials, including their synthesis strategies and the effects of geometric confinement on magnetic properties. These materials, including metals, alloys, and ceramics, find applications in green energy, information storage, and biomedicine. Research in this area is important for both technological applications and understanding magnetic anisotropy and interactions.
PROGRESS IN MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Liang Sun, Kuo-She Li, Hong-Wei Li, Dun-Bo Yu, Yang Luo, Jin-Ling Jin, Shuo Lu, Ning-Tao Quan
Summary: Melt-spun Y16Fe78B6 ribbons were prepared using the melt-spinning technique with pure Y, Fe, and Fe-B alloy in argon. The ribbons mainly consisted of Y2Fe14B, YFe2, and alpha-Fe phases. The amorphous phase appeared at a wheel velocity of >35 m·s(-1). The ribbons prepared at the optimum wheel velocity and heat treatments exhibited coercivity, remanence, and maximum energy product of 239.5 kA·m(-1), 0.61 T, and 32.7 kJ·m(-3) respectively. Investigation of the Henkel plots of the ribbons revealed that intergrain exchange coupling enhanced the remanence. The coercivity mechanism of the ribbons prepared at 35 m·s(-1) was mainly controlled by inhomogeneous pinning of domain walls. The phase component and magnetic properties changed with annealing temperature and time. The optimum magnetic properties were obtained with the ribbon quenched at 35 m·s(-1) and annealed at 700 degrees C for 10 min.
Article
Energy & Fuels
Anna Przybyl, Piotr Gebara, Roman Gozdur, Krzysztof Chwastek
Summary: The paper describes the magnetic properties of different praseodymium-dysprosium ribbons using the modified Harrison model, and also includes microstructural studies. The modification of the model allows for more freedom in the modeling process.
Article
Engineering, Electrical & Electronic
Peipei Cao, Huali Wang, Kaijie Zhou, Xue Ni
Summary: In this paper, a motion noise reduction method based on variational mode extraction (VME) using variational mode decomposition (VMD) is proposed for the low-frequency magnetic field measurement system of superconducting quantum interference device (SQUID). The VME method can accurately remove the motion noise of the sensor SQUID with advantages of small computation and fast convergence speed.
IEEE SENSORS JOURNAL
(2021)
Article
Engineering, Electrical & Electronic
Mohammed El Yaagoubi, Stefan Haas, Dietmar Schwegler
Summary: This study investigated the magnetic orientation of hard ferrite filled elastomer during the vulcanization process. A coil integrated in the injection moulding tool was used to orient the particles, with magnetically conductive and non-magnetically conductive steels used to conduct the magnetic field. Demonstrators with radially oriented and axially oriented orientations were injected, demagnetized, magnetized, and evaluated for magnetic signals.
SENSORS AND ACTUATORS A-PHYSICAL
(2021)
Article
Materials Science, Multidisciplinary
Dong-Qin Ma, Zi-Hui Ge, Yun-Fe Cao, He-Wei Ding, Yan-Fei Jiang, Ji-Bing Sun
Summary: The spinodal decomposed Cu-Ni-Fe alloy can exhibit both hard magnetic properties and excellent mechanical toughness, corrosion resistance, and cold workability. The structure formed through the decomposition of ? ? ?1 + ?2 inside the grains plays a key role in endowing the ribbons with hard-magnetic properties. The main factors influencing the magnetic properties include shape anisotropy of ?1 and ?2, the concentration of Fe, Co, Ni in the ?2 phase, and the content of the ? phase.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Chemistry, Inorganic & Nuclear
Alessandro Giuseppe D'Aloia, Antonio Di Francesco, Valerio De Santis
Summary: A novel computational method for reproducing hysteresis loops of hard magnetic materials is proposed in this study, showing significant improvement in terms of computational performance compared to classical models. The method utilizes a different approach in modeling the hysteron effect, which allows for accurate modeling of a large class of hysteresis loops. Additionally, the method permits modeling of the temperature effect on magnetization of neodymium magnets, which is essential for designing electrical machines.
Article
Engineering, Electrical & Electronic
Mohammed El Yaagoubi, Manuel Schroedl, Dietmar Schwegler, Bernhard Muenster
Summary: This study developed strontium ferrite filled thermoplastic elastomers and analyzed the influence of filler content on mechanical and magnetic properties.
SENSORS AND ACTUATORS A-PHYSICAL
(2022)
Article
Materials Science, Multidisciplinary
Kinjal Gandha, Rakesh P. Chaudhary, Matthew J. Kramer, Ryan T. Ott, Durga Paudyal, I. C. Nlebedim
Summary: This work systematically studies the Ce-Co based 1:5 permanent magnet alloys and investigates the impact of Co:Fe ratio on the hard-magnetic properties. The addition of Cu is found to improve the mutual solubility of Fe in the 1:5 phase. The research reveals that lower Fe content leads to a homogeneous microstructure and good magnetic properties, while a certain range of Fe content may result in the evolution of other phases. Furthermore, adding Fe enhances magnetization and Curie temperature, while increasing Cu content enhances coercivity.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Multidisciplinary Sciences
M. Suppan, C. Huber, K. Mathauer, C. Abert, F. Brucker, J. Gonzalez-Gutierrez, S. Schuschnigg, M. Groenefeld, I Teliban, S. Kobe, B. Saje, D. Suess
Summary: In this work, the in-situ alignment of single-crystal magnetic particles inside a polymer matrix using fused filament fabrication is demonstrated. The strontium hexaferrite particles can be well aligned, while the samarium iron nitride particles cannot.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Multidisciplinary
Harshida Parmar, Xubo Liu, Kinjal Gandha, M. Parans Paranthaman, Ikenna C. Nlebedim
Summary: This study investigates the effect of magnetic field annealing on relieving the stress induced during milling of Nd-Fe-B sintered magnets, and explores the influence of MA processing parameters and particle size on the magnetic properties. The results demonstrate that magnetic field annealing is more effective in improving the magnetic properties of larger particles compared to finer particles. Computational study supports the role of particle surface defects in bimodal particle distribution seen experimentally. Magnetic field annealed powder has been used successfully to develop bonded magnets with a density of 4.6 g.cm 3, consisting of 75% magnetic powder and polyamide 12 (nylon 12) polymer binder, resulting in an energy product of 11.3 MGOe.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
J. Vergara, C. Favieres, V Madurga
Summary: Hard magnetic MnBi films were obtained through appropriate heat treatments. Magnetic measurements and MFM confirmed the correlation between magnetic domains and MnBi grains in the film. Extra Mn layers did not affect the structure and magnetism significantly, while the addition of Bi layers changed the magnetic structure of MnBi grains.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Huan Liu, Xinglin Zhang, Congyu Liao, Haobin Dong, Zheng Liu, Xiangyun Hu
Summary: A novel magnetic anomaly detection (MAD) method based on structured low-rank (SLR) and total variation (TV) regularization constraints is proposed in this article, which improves signal-to-noise ratio and maintains clean boundaries. Comparing with other methods, the proposed SLR-TV method achieves the highest SNR improvement and the best structural similarity improvement (SSIM) in low SNR conditions.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2023)
Article
Nanoscience & Nanotechnology
K. R. Fast, J. A. Thibault, V. T. K. Sauer, M. G. Dunsmore, A. Kav, J. E. Losby, Z. Diao, E. J. Luber, M. Belov, M. R. Freeman
Summary: Measurements of magnetic torque are commonly performed on a single axis, useful for hysteresis measurements of thin film structures. Introducing a technique to measure the full magnetic torque vector on micro- and nano-scale materials using a modified resonant torque sensor. Optical position-sensitive detection is used to read out the resulting displacements, with measurements compared against micromagnetic simulations to enhance signal interpretation.
Article
Chemistry, Physical
Jin Gu Kang, Hyejin Jang, Jun Ma, Qun Yang, Khalid Hattar, Zhu Diao, Renliang Yuan, Jianmin Zuo, Sanjiv Sinha, David G. Cahill, Paul Braun
Summary: A surprising nanostructuring route led to ultralow thermal conductivity in a large-unit-cell oxide crystal by introducing close-packed nanoscale pores, with the thermal conductivity strongly dependent on pore size and the electrical conductivity reducing significantly relative to dense Fe3O4.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Review
Medicine, Legal
Lee C. Bushong, Zhu Diao
Summary: This paper examines a pediatric hyperthermia homicide and reconstructs the scene to analyze the thermal parameters of the room and environment. It provides a time-window of exposure necessary to elicit hyperthermia under specific conditions.
JOURNAL OF FORENSIC SCIENCES
(2022)
Article
Physics, Applied
Zexiang Hu, Jean Besbas, Ross Smith, Niclas Teichert, Gwenael Atcheson, Karsten Rode, Plamen Stamenov, J. M. D. Coey
Summary: Toggle switching behavior is observed in thin films of sperimagnetic amorphous DyxCo1-x and TbxCo1-x irradiated with single fast laser pulses. The films exhibit strong local random anisotropy, and subsequent laser pulses lead to partial re-switching of a decreasing amount of material, resulting in a granular structure. The toggle switching is attributed to the temperature-dependent ratio of local anisotropy to exchange.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
M. G. Dunsmore, J. A. Thibault, K. R. Fast, V. T. K. Sauer, J. E. Losby, Z. Diao, M. Belov, M. R. Freeman
Summary: Micrometer diameter bilayers of NiFe and CoO were used to study exchange bias effects on nanomechanical resonators. By modifying the resonator structure, we were able to measure three orthogonal torque components simultaneously. We observed anisotropies associated with interfacial exchange coupling effects and probed in-plane anisotropies through different experiments.
Article
Materials Science, Multidisciplinary
J. M. D. Coey, D. Givord, D. Fruchart
Summary: This article presents energy-level diagrams for cubic metallic Fe4N and Mn4N, describing their magnetic properties. The magnetic ordering and tunable ferrimagnetic compensation in Mn3-xM'N-x metallic perovskites are discussed, along with the characteristics of topological ferrimagnets. The article emphasizes the wide range of applications in magnetic structures, magnetotransport, magnetocaloric, and magnetovolume effects in metallic perovskites.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2022)
Article
Mechanics
Sruthy Poulose, Jennifer A. Quirke, Plamen Stamenov, Matthias E. Mobius, J. M. D. Coey
Summary: In this study, pendant droplets of water and paramagnetic solutions were examined in the presence of uniform and nonuniform magnetic fields. The findings showed that the surface tension of water droplets was minimally affected by a uniform magnetic field, while the magnetic field gradient was able to deform the droplets and affect their density. The dynamic measurements revealed that the magnetic field had no significant impact on the pinch-off dynamics.
Article
Physics, Applied
Jinu Kurian, Aleena Joseph, Salia Cherifi-Hertel, Ciaran Fowley, Gregor Hlawacek, Peter Dunne, Michelangelo Romeo, Gwenael Atcheson, J. M. D. Coey, Bernard Doudin
Summary: He+ ion irradiation is used to pattern multiple areas of Pt/Co/W films with different irradiation doses in Hall bars, resulting in a landscape of perpendicular magnetic anisotropy. This enables selective multilevel current-induced switching, with full control of the position and order of the individual switching elements. Key pattern design parameters are specified, offering a scalable approach for multilevel switching devices.
APPLIED PHYSICS LETTERS
(2023)
Review
Physics, Condensed Matter
Tim A. Butcher, J. M. D. Coey
Summary: This article provides an overview of the effect of a magnetic field gradient on fluids with linear magnetic susceptibilities. It shows the equivalence between the magnetic field gradient force and the concentration gradient force for paramagnetic species in solution in incompressible fluids. The magnetic field gradient and concentration gradient forces are approximations of the Kelvin force and Korteweg-Helmholtz force densities, respectively. The criterion for the appearance of magnetically induced convection is derived, and experimental work involving magnetically induced convection is reviewed.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Physics, Applied
Yangkun He, J. M. D. Coey, Zsolt Gercsi
Summary: Fully compensated ferrimagnetic half metals have attracted great attention in spintronics. Unlike previous calculations based on hypothetical ordered alloys, we investigated existing solid solution series using Co1-xCrxS2 as an example. Our calculations reveal a low-spin state for Cr, consistent with early experiments, and a fully compensated ferrimagnetic half metal with a Curie temperature above room temperature at x approximate to 0.33. This study demonstrates the method of combining two half metals with light and heavy 3d metals in a solid solution to achieve compensation, where atomic disorder does not compromise the desired properties.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
K. E. Siewierska, H. Kurt, B. Shortall, A. Jha, N. Teichert, G. Atcheson, M. Venkatesan, J. M. D. Coey, Z. Gercsi, K. Rode
Summary: The cubic Heusler alloy Ru2-xMn1+xAl, grown as a thin film on MgO and MgAl2O4 substrates, is a spin-polarised ferrimagnetic metal with weak magnetocrystalline anisotropy. Unlike Mn2RuxGa, it does not exhibit ferrimagnetic compensation or large magneto-galvanic effects, which are attributed to a combination of atomic order and hybridisation with the group 13 element Al or Ga. The spin polarisation is around 50% to 60%, with a gap in the density of states just above the Fermi level in fully ordered compounds.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Editorial Material
Physics, Multidisciplinary
Zsolt Gercsi, Yangkun He, J. M. D. Coey
PHYSICAL REVIEW LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Sruthy Poulose, Yara Alvarez-Brana, Lourdes Basabel-Desmonts, Fernando Benito-Lopez, John Michael David Coey
Summary: Water evaporation is studied in confined environments, and it is found that the magnetic field has a greater effect on the evaporation rate in microchannels compared to beakers. The evaporation rate in microchannels is double that of beakers, but lower than expected for an open surface in still air. The magnetic enhancement is due to the gradient of the applied magnetic field, which affects the isomeric populations in the vapor and increases the evaporation rate.
IEEE MAGNETICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Yangkun He, Simon Lenne, Zsolt Gercsi, Gwenael Atcheson, Jack O'Brien, Daniel Fruchart, Karsten Rode, J. M. D. Coey
Summary: This article investigates the spin structure of Mn4N films and its influence on the magnetotransport properties.
Article
Materials Science, Multidisciplinary
Rui Zhang, Zsolt Gercsi, M. Venkatesan, Karsten Rode, J. M. D. Coey
Summary: Calculations suggest that ordered Heusler alloys with 18 valance electrons could exhibit a variety of unusual electronic and magnetic states. Experimental results show that the as-cast alloys are all Pauli paramagnets with some degree of B2-type ordering, and prolonged annealing leads to phase segregation. Density functional theory calculations confirm that different atomic arrangements in the interpenetrating face-centered cubic sublattices could lead to unusual magnetic properties, but disorder destroys both magnetism and semiconductivity.
