Article
Physics, Multidisciplinary
Kevin J. A. Franke, Colin Ophus, Andreas K. Schmid, Christopher H. Marrows
Summary: Through micromagnetic simulations and analytical modeling, it has been found that Neel walls can be formed even in the absence of a Dzyaloshinskii-Moriya interaction, but with uniaxial in-plane magnetic anisotropy. The ability to switch between Bloch and Neel walls can be achieved via modulation of both in-plane and perpendicular magnetic anisotropy, opening up possibilities for electric field control of domain wall type with small applied voltages.
PHYSICAL REVIEW LETTERS
(2021)
Article
Nanoscience & Nanotechnology
J. Askey, M. Hunt, W. Langbein, S. Ladak
Summary: Cylindrical magnetic nanowires have been extensively studied for their unique topology and dynamic properties. This study numerically investigates the domain wall magnetization textures of nickel nanowires and discovers a new domain wall type that combines aspects of both Bloch point walls and asymmetric transverse walls.
Review
Plant Sciences
Kouki Yoshida, Shingo Sakamoto, Nobutaka Mitsuda
Summary: "To mitigate the effects of global warming and preserve fossil fuel resources, increased exploitation of plant-based materials and fuels is necessary. This review discusses recent advances in engineering plant cell walls through genetic manipulations, focusing on wild-type and mutant-based approaches. Genome-editing technologies have made mutant-based cell wall engineering feasible, paving the way for artificial wood production via complex genetic manipulations."
PLANT AND CELL PHYSIOLOGY
(2021)
Article
Materials Science, Coatings & Films
Jai-Lin Tsai, Chun-Yu Sun, Jun-Kai Lin, Xue-Chang Lu, Sin-Han Huang
Summary: The (001) textured L1(0) FePt film is a promising candidate material for future heat assisted magnetic recording technology. The material of the epitaxial intermediate layer for the FePt based granular film was chosen considering the surface energy and lattice mismatch between FePt and MgO-based materials. In this study, a (00L) textured FePt (Ag, C)/ MgTiOBN/CrRu film was prepared and the MgTiOBN intermediate layer was thoroughly explored. The FePt film showed high perpendicular magneto-crystalline anisotropy and out-of-plane coercivity, and exhibited lower in-plane magnetization and nonuniform trapezoidal island-like grains.
SURFACE & COATINGS TECHNOLOGY
(2022)
Article
Physics, Multidisciplinary
D. Bazeia, M. A. Marques, M. Paganelly
Summary: This work presents a method to manipulate the internal structure of localized configurations of the Bloch wall type. By considering a three-field model and using a first order formalism based on energy minimization, it is shown that the geometric arrangement of the Bloch wall can be changed by decoupling the third field, leading to diverse modifications of its internal structure. This procedure captures effects beyond the standard situation and can be applied in the study of magnetization in magnetic materials at the nanoscale.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Multidisciplinary Sciences
Chang Liu, Hasi Yu, Aline Voxeur, Xiaolan Rao, Richard A. Dixon
Summary: Modifying lignin or cellulose in transgenic plants can induce defense responses and negatively affect growth, but bypassing endogenous pectin signaling pathways is required for engineering plant cell walls.
Article
Materials Science, Multidisciplinary
A. De Riz, J. Hurst, M. Schoebitz, C. Thirion, J. Bachmann, J. C. Toussaint, O. Fruchart, D. Gusakova
Summary: There are two types of domain walls in magnetically soft cylindrical nanowires: the transverse-vortex wall (TVW) and the Bloch-point wall (BPW). Recent research has shown that the previously overlooked Oersted field associated with an electric current plays a key role in stabilizing BPW and achieving high speeds above 600 m/s. The switching of the azimuthal circulation of BPW to match that of the Oersted field occurs above a threshold current scaling with 1/R3 (R is the wire radius), involving mechanisms related to the nucleation and/or annihilation of Bloch points.
Article
Physics, Multidisciplinary
Natascha Hedrich, Kai Wagner, Oleksandr V. Pylypovskyi, Brendan J. Shields, Tobias Kosub, Denis D. Sheka, Denys Makarov, Patrick Maletinsky
Summary: The study demonstrated manipulation and interaction of antiferromagnetic domain walls using isolated 180 degree domain walls in a single crystal of Cr2O3, proposing a memory architecture based on topographically defined antiferromagnetic domain walls. These results advance the understanding of domain wall mechanics in antiferromagnets.
Article
Physics, Applied
Diego Caso, Pablo Tuero, Javier Garcia, Konstantin Y. Guslienko, Farkhad G. Aliev
Summary: By adjusting parameters such as the length of the nanowire, excitation frequency, microwave pulse duration, and spin-current value, reversible transitions between single-vortex and Bloch-point vortex structures can be achieved, enabling fast and efficient switching of nanomagnets in magnetic memories.
PHYSICAL REVIEW APPLIED
(2023)
Article
Materials Science, Multidisciplinary
M. S. Wornle, P. Welter, M. Giraldo, T. Lottermoser, M. Fiebig, P. Gambardella, C. L. Degen
Summary: Using nanoscale scanning diamond magnetometry and second-harmonic-generation microscopy, we elucidate the domain-wall structure of the model antiferromagnet Cr2O3, finding that 180 degrees domain walls are predominantly Bloch-like and can coexist with Neel walls in crystals with significant in-plane anisotropy. Furthermore, we report quantitative measurements of the domain-wall width and surface magnetization. Our results offer fundamental insights and an experimental approach for understanding domain walls in pure, intrinsic antiferromagnets, with implications for achieving electrical control of domain-wall motion in antiferromagnetic compounds.
Article
Nanoscience & Nanotechnology
Qianwei Huang, Jiyuan Yang, Zibin Chen, Yujie Chen, Matthew J. Cabral, Haosu Luo, Fei Li, Shujun Zhang, Yulan Li, Zonghan Xie, Houbing Huang, Yiu-Wing Mai, Simon P. Ringer, Shi Liu, Xiaozhou Liao
Summary: This study demonstrates the feasibility of generating CDWs through mechanical stress and investigates the formation mechanism through experiments and simulations.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Engineering, Civil
Zaid Momani, Eyosias Beneberu, Nur Yazdani
Summary: The research found that the movement of MSE retaining walls is influenced by soil pore pressure, stability of reinforcement, and reinforcement length, while it is unaffected by concrete strength. Soil cohesion has a minor effect, and the movement of walls reinforced with flexible geogrids increases by 13-20 mm compared to steel grid reinforcement.
FRONTIERS OF STRUCTURAL AND CIVIL ENGINEERING
(2021)
Article
Materials Science, Multidisciplinary
Hong Hong, Dong-Xue Liu, Jun Li, Jun-Ming Li, Li-Qian Wu, Bo Yang, Qing-Qi Cao, Dun-Hui Wang
Summary: Magnetic field-assisted electrocatalytic water splitting is an effective strategy to improve the properties of electrocatalysts, but most methods require the exertion of an external magnetic field during electrochemical reactions, resulting in high cost and challenging magnetic field manipulation. In this study, a bias magnetic field self-supplied by a ferromagnetic electrocatalyst of FePt is utilized instead of an external magnetic field. The remanence state of the FePt film with the assistance of the bias magnetic field shows a significantly lower overpotential (229 mV) during the hydrogen evolution reaction compared to its demagnetization state (283 mV), indicating that the remanence in ferromagnetic electrocatalysts can enhance catalytic performance by reducing domain walls.
Article
Engineering, Electrical & Electronic
Syuta Honda, Yuki Kaiya, Hiroyoshi Itoh, Tomokatsu Ohsawa
Summary: The magnetic domain in a perpendicularly magnetized ferromagnetic metal can move through a perpendicularly magnetized ferromagnetic insulator via spin-transfer torque. This phenomenon can be applied to achieve racetrack memory. The domain exhibits different behaviors when passing through insulators of different shapes, with a rectangular insulator causing an unstable structure and a zigzag insulator increasing the domain velocity.
IEEE TRANSACTIONS ON MAGNETICS
(2021)
Article
Metallurgy & Metallurgical Engineering
I. M. Izhozherov, E. Zh Baikenov, V. V. Zverev
Summary: This study investigates the domain structures in a 200 nm thick Co(0001) film containing Bloch lines, revealing the presence of Bloch points in cases where the domain walls are vortex-like. The transformation processes of domain structures containing Bloch lines during film magnetization and subsequent decrease in magnetic field are examined, with analysis on the configurations of magnetization in Bloch lines showing the emergence of both vertical and horizontal segments upon the application of a magnetic field at an angle to the film plane.
PHYSICS OF METALS AND METALLOGRAPHY
(2021)
Article
Multidisciplinary Sciences
S. R. Tauchert, M. Volkov, D. Ehberger, D. Kazenwadel, M. Evers, H. Lange, A. Donges, A. Book, W. Kreuzpaintner, U. Nowak, P. Baum
Summary: The research shows that when a nickel film is subjected to ultrashort laser pulses, it loses its magnetic order within femtosecond timescales and forms a unique population of anisotropic high-frequency phonons. These results highlight the general importance of polarized phonons in non-equilibrium dynamics and phase transitions.
Article
Physics, Applied
R. Khamtawi, W. Daeng-am, P. Chureemart, R. W. Chantrell, J. Chureemart
Summary: An exchange bias (EB) model is developed to study the effect of crucial parameters on the exchange bias field of an AFM/FM system. The simulation results show a strong dependence of the exchange bias field on the energy barrier dispersion determined by the AFM anisotropy constant and the physical microstructure. By optimizing the values of these parameters, the maximum setting fraction related to the exchange bias field can be achieved. The validity of the EB model is confirmed by the good agreement with previous experimental works.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Multidisciplinary Sciences
Sutee Sampan-A-Pai, Rattaphon Phoomatna, Worawut Boonruesi, Andrea Meo, Jessada Chureemart, Richard F. L. Evans, Roy W. Chantrell, Phanwadee Chureemart
Summary: This theoretical study investigates the influence of finite size and temperature on the mechanism of magnetization switching in CoFeB-MgO based magnetic tunnel junctions (MTJs). The results reveal the strong dependence of the incoherent switching process on system size and temperature, with temperature leading to decreased switching time.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Applied
Andrea Meo, K. Pituso, K. Pornpitakpong, A. Suntives, S. E. Rannala, R. W. Chantrell, P. Chureemart, J. Chureemart
Summary: We have developed a code to accurately extract the signal-to-noise ratio (SNR) of the magnetic film in a recording medium. By separating the remanence and transition contributions from the overall spatial noise, our approach gives results that are consistent with the analysis performed using Seagate proprietary software. Furthermore, we apply this method to simulations of heat-assisted magnetic recording (HAMR) dynamics and compare it with experimental spin-stand measurements, which will help to improve the writing performance of HAMR by reducing the noise arising from the medium.
PHYSICAL REVIEW APPLIED
(2023)
Review
Materials Science, Multidisciplinary
Ritwik Mondal, Levente Rozsa, Michael Farle, Peter M. Oppeneer, Ulrich Nowak, Mikhail Cherkasskii
Summary: The dynamics of magnetic moments involve precession around the magnetic field direction and relaxation towards the field to minimize energy. At ultrafast time scales, the direction of magnetic moment and angular momentum become separated due to inertial effects. This inertial dynamics leads to additional high-frequency modes in the excitation spectrum of magnetic materials. In this review, recent theoretical and experimental advancements in this field are discussed, along with open challenges and opportunities in the detection and potential applications of inertial spin dynamics.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Nguyen Thanh Binh, Sarah Jenkins, Sergiu Ruta, Richard F. L. Evans, Roy W. Chantrell
Summary: We computationally studied the properties of higher-order magnetic anisotropy constants in an L1(0)/A1-FePt core-shell system with a strong second-order Fe-Pt anisotropy component. A surprising fourth-order anisotropy constant K-2 was induced by the core-shell structure, with its magnitude reaching a peak at a core-size ratio of R approximately 0.50. Moreover, we found that K-2 scales with the normalized magnetization by (M/M-s)(2.2) below the Curie temperature, deviating from the expected scaling exponent of 10 predicted by the Callen-Callen theory. Our analytical model explains that K-2 arises from the canting of the core and shell magnetization and successfully justifies the scaling exponent obtained from numerical simulation.
Article
Materials Science, Multidisciplinary
Tobias Dannegger, Andras Deak, Levente Rozsa, E. Galindez-Ruales, Shubhankar Das, Eunchong Baek, Mathias Klaeui, Laszlo Szunyogh, Ulrich Nowak
Summary: In this study, ab initio calculations were performed to investigate the tensorial exchange interactions of hematite, and a semiclassical Heisenberg spin model was used to understand its magnetic properties. Atomistic spin dynamics simulations were carried out to calculate the equilibrium properties and phase transitions of hematite, particularly the Morin transition. The computed isotropic and Dzyaloshinskii-Moriya interactions were found to agree well with experimental measurements of the Neel temperature and weak ferromagnetic canting angle. Our simulations revealed the delicate balance between dipole-dipole interactions and on-site anisotropies in determining the magnetic phase of the material. Comparison with spin-Hall magnetoresistance measurements on a hematite single crystal showed deviations of the critical behavior at low temperatures, which were attributed to the quantum nature of the fluctuations driving the phase transitions.
Article
Materials Science, Multidisciplinary
Markus Weissenhofer, Francesco Foggetti, Ulrich Nowak, Peter M. Oppeneer
Summary: Efficient and fast manipulation of antiferromagnets is achieved by utilizing laser-induced ultrafast demagnetization and spin-polarized hot-electron currents, which can excite spin dynamics and exert spintransfer torque on femtosecond timescales in antiferromagnetic Mn2Au. A spin-valve-type trilayer structure consisting of Fe|Cu|Mn2Au is studied using quantitative superdiffusive transport and atomistic spin model calculations. The results show that the Mn2Au layer can be switched within a few picoseconds through femtosecond spin-transfer torques, and high-frequency spin waves up to several THz can be excited in Mn2Au.
Article
Materials Science, Multidisciplinary
Hannah Lange, Sergiy Mankovsky, Svitlana Polesya, Markus Weissenhofer, Ulrich Nowak, Hubert Ebert
Summary: Recently, there has been a lot of attention on the interplay between spin and lattice degrees of freedom due to its importance in various phenomena and applications. This work provides a systematic analysis of spin-lattice interactions in different magnetic materials and focuses on the role of lattice symmetries and dimensions, magnetic order, and the relevance of spin-lattice interactions for angular momentum transfer and magnetic frustration. The authors use a recently developed scheme and an embedded cluster approach to efficiently calculate spin-lattice interaction tensors and benchmark the performance of the scheme.
Article
Materials Science, Multidisciplinary
Jack B. Collings, Ricardo Rama-Eiroa, Ruben M. Otxoa, Richard F. L. Evans, Roy W. Chantrell
Summary: We propose a general approach to calculate the effective anisotropy field for magnetic spins based on the Landau-Lifshitz-Gilbert equation. This approach is applicable to all orders of anisotropies, including higher-order combinations often found in functional magnetic materials. The anisotropies are represented in terms of spherical harmonics, allowing for rational temperature scaling and providing a unified framework for numerical simulations.
Article
Materials Science, Multidisciplinary
Markus Weissenhofer, Ulrich Nowak
Summary: Magnetic skyrmions are promising for spintronic applications, but face challenges like the skyrmion Hall effect and inefficient detection. This study investigates the current-driven and Brownian dynamics of skyrmions in ferrimagnetic materials with a compensation point. Results show a nonmonotonic temperature dependence of the velocities and the diffusion coefficient, with a strong enhancement at the angular momentum compensation temperature. These findings provide a new pathway for the efficient manipulation of skyrmion dynamics via temperature.
Article
Materials Science, Multidisciplinary
Lucas Winter, Sebastian Grossenbach, Ulrich Nowak, Levente Rozsa
Summary: Recent research has shown that magnetization dynamics exhibit not only precession but also nutation on ultrashort timescales, especially in high-frequency magnetic fields. Ferromagnets and antiferromagnets can achieve fast spin switching under different types of magnetic fields, which further advances the development of ultrafast data writing.
Article
Materials Science, Multidisciplinary
Markus Weissenhofer, Severin Selzer, Ulrich Nowak
Summary: The Brownian motion of domain walls in uniaxial and biaxial ferromagnetic nanowires is studied, comparing spin dynamics simulations with analytical calculations within the framework of a collective coordinate approach. The results demonstrate that the interplay between spatial and angular dynamics gives rise to a complex time dependence of the MSD in biaxial nanowires and to a drastically reduced diffusion coefficient in uniaxial nanowires, analogous to magnetic skyrmions. This diffusion suppression is also responsible for the peculiar temperature dependence of the diffusion coefficient in biaxial systems: while it is found to scale linearly with temperature up to a certain threshold, the emergence of a Walker breakdown of Brownian motion is responsible for a reduction of the diffusion coefficient with increasing temperature above this threshold.
Article
Materials Science, Multidisciplinary
Severin Selzer, Leandro Salemi, Andras Deak, Eszter Simon, Laszlo Szunyogh, Peter M. Oppeneer, Ulrich Nowak
Summary: This study investigates the current-induced switching in Mn2Au through first principles calculations and atomistic spin dynamics simulations. It reveals that thermal activation is crucial for overcoming the energy barrier in the switching process.
Article
Materials Science, Multidisciplinary
Verena Brehm, Martin Evers, Ulrike Ritzmann, Ulrich Nowak
Summary: In this study, the magnetic proximity effect in multilayer systems composed of different ferro-and antiferromagnetic materials was investigated using an atomistic spin model. The results show that the magnetic order in the central layer is enhanced, even in the case of an antiferromagnet surrounded by ferromagnetic materials.
