Article
Chemistry, Multidisciplinary
Hendrik Meer, Felix Schreiber, Christin Schmitt, Rafael Ramos, Eiji Saitoh, Olena Gomonay, Jairo Sinova, Lorenzo Baldrati, Mathias Klaeui
Summary: Researchers have unraveled the mechanism of current-induced magnetic switching in insulating antiferromagnet/heavy metal systems using concurrent transport and magneto-optical measurements. Different final states of the switching in specially engineered NiO/Pt bilayers devices were observed with different electrical pulsing and device geometries, attributed to the thermomagnetoelastic switching mechanism combined with thermal excitations. This noncontact mechanism provides a potential explanation for previously reported contradicting observations of switching final state attributed to spin-orbit torque mechanisms.
Article
Physics, Applied
J. J. F. Heitz, L. Nadvornik, V Balos, Y. Behovits, A. L. Chekhov, T. S. Seifert, K. Olejnik, Z. Kaspar, K. Geishendorf, V Novak, R. P. Campion, M. Wolf, T. Jungwirth, T. Kampfrath
Summary: The study demonstrates complete suppression of terahertz-pulse-induced resistance switching in antiferromagnetic CuMnAs thin films using ultrafast gating. Gating functionality is achieved through optically generated transiently conductive parallel channels in the semiconductor substrate, with suppression timescale determined by photocarrier lifetime. Effects observed are mediated primarily by the substrate, with potential application for transient low-power masking of structured areas with feature sizes of about 200 nm and smaller.
PHYSICAL REVIEW APPLIED
(2021)
Article
Multidisciplinary Sciences
Sonka Reimers, Dominik Kriegner, Olena Gomonay, Dina Carbone, Filip Krizek, Vit Novak, Richard P. Campion, Francesco Maccherozzi, Alexander Bjorling, Oliver J. Amin, Luke X. Barton, Stuart F. Poole, Khalid A. Omari, Jan Michalicka, Ondrej Man, Jairo Sinova, Tomas Jungwirth, Peter Wadley, Sarnjeet S. Dhesi, Kevin W. Edmonds
Summary: This study reveals that the antiferromagnetic (AF) domain structure in CuMnAs thin films is dominated by nanoscale structural twin defects, which play a crucial role in determining the location and orientation of AF domain walls. The results provide insights into the interplay of crystalline defects, strain, and magnetic ordering in AF materials, offering a route to optimize device performance.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Chong Wang, Yang Gao, Di Xiao
Summary: In this study, the intrinsic nonlinear Hall effect is identified as a significant contributor to detecting the reversal of the Neel vector, independent of relaxation time. The nonlinear Hall conductivity in the antiferromagnetic metal tetragonal CuMnAs can reach the order of mA/V2 and shows a qualitative dependence on the chemical potential. The survey of magnetic point groups provides guidelines for discovering more antiferromagnetic materials with intrinsic nonlinear Hall effect.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Jia Xu, Jing Xia, Xichao Zhang, Chao Zhou, Dong Shi, Haoran Chen, Tong Wu, Qian Li, Haifeng Ding, Yan Zhou, Yizheng Wu
Summary: We experimentally demonstrate that the switching rate of the antiferromagnetic (AFM) domain can be significantly enhanced by more than 2 orders of magnitude through applying an alternating square-wave field on a Fe/CoO bilayer. This finding opens up new opportunities for designing antiferromagnet-based spintronic devices.
PHYSICAL REVIEW LETTERS
(2022)
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
Multidisciplinary Sciences
Sevdenur Arpaci, Victor Lopez-Dominguez, Jiacheng Shi, Luis Sanchez-Tejerina, Francesca Garesci, Chulin Wang, Xueting Yan, Vinod K. Sangwan, Matthew A. Grayson, Mark C. Hersam, Giovanni Finocchio, Pedram Khalili Amiri
Summary: There is growing interest in using antiferromagnetic materials for memory devices, with recent studies showing complications in interpreting resistive switching signals generated by high current densities in antiferromagnetic/heavy metal bilayers. Arpaci et al have introduced an experimental protocol to distinguish between magnetic and nonmagnetic switching signals in such structures, showcasing their method in IrMn3/Pt devices. The researchers utilized a six-terminal double-cross device to demonstrate reversible switching in the presence of IrMn3, effectively eliminating any non-magnetic switching artifacts.
NATURE COMMUNICATIONS
(2021)
Article
Multidisciplinary Sciences
Tomoya Higo, Kouta Kondou, Takuya Nomoto, Masanobu Shiga, Shoya Sakamoto, Xianzhe Chen, Daisuke Nishio-Hamane, Ryotaro Arita, Yoshichika Otani, Shinji Miwa, Satoru Nakatsuji
Summary: This study demonstrates the perpendicular and full spin-orbit torque switching of an antiferromagnetic binary state. The researchers use the chiral antiferromagnet Mn3Sn and fabricate heavy-metal/Mn3Sn heterostructures by molecular beam epitaxy. The experimental results show that the perpendicular octupole polarization in a 30-nanometre-thick Mn3Sn film can achieve 100% switching with a critical current density of less than 15 megaamperes per square centimetre. The study reveals the significance of the perpendicular geometry between the current-induced spin accumulation and the octupole polarization for spin-orbit torque efficiency.
Article
Physics, Applied
S. F. Poole, L. X. Barton, M. Wang, P. Manuel, D. Khalyavin, S. Langridge, K. W. Edmonds, R. P. Campion, V. Novak, P. Wadley
Summary: This study describes measurements of the uniaxial magnetic anisotropy and spin-flop rotation of the Neel vector in antiferromagnetic CuMnAs thin films using neutron diffraction. The experimental results indicate that films as thin as 20 nm undergo a spin-flop transition under magnetic fields, and neutron measurements can provide a quantitative determination of the spin-flop rotation throughout the antiferromagnet layer.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Hendrik Meer, Stephan Wust, Christin Schmitt, Paul Herrgen, Felix Fuhrmann, Steffen Hirtle, Beatrice Bednarz, Adithya Rajan, Rafael Ramos, Miguel Angel Nino, Michael Foerster, Florian Kronast, Armin Kleibert, Baerbel Rethfeld, Eiji Saitoh, Benjamin Stadtmueller, Martin Aeschlimann, Mathias Klaeui
Summary: The antiferromagnetic order in NiO/Pt thin film heterostructures can be altered by optical pulses. Using X-ray magnetic linear dichroism, the optically induced creation of antiferromagnetic domains can be visualized. The effect of different laser polarizations on domain formation can be studied to identify polarization-independent creation of 180 degrees domain walls and domains with different Neel vector orientations. By varying irradiation parameters, the switching mechanism was determined to be thermally induced. This study demonstrates the potential for optically creating antiferromagnetic domains, an important advancement in the functionalization of all optical switching mechanisms in antiferromagnets.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
M. Yang, Q. Li, T. Wang, B. Hong, C. Klewe, Z. Li, X. Huang, P. Shafer, F. Zhang, C. Hwang, W. S. Yan, R. Ramesh, W. S. Zhao, Y. Z. Wu, Xixiang Zhang, Z. Q. Qiu
Summary: This study investigates the mechanism of current-induced switching of antiferromagnetic (AFM) order using measurements of Hall resistance and x-ray magnetic linear dichroism. The researchers identified both magnetic and nonmagnetic contributions to the current-induced changes and quantitatively determined the percentage of spin switching. They also found that the thermal effect on CoO magnetic switching varies with the film structure.
Article
Chemistry, Multidisciplinary
Hang Xie, Nan Zhang, Yuteng Ma, Xin Chen, Lin Ke, Yihong Wu
Summary: Recently, orbital Hall current has been studied as an alternative method for magnetization switching in ferromagnets. In this study, we found that the antiferromagnetic state in Mn3Sn/Cr can be electrically switched, even though the spin Hall angle of Cr is smaller than heavy metal-based heterostructures. However, the efficiency of spin-to-charge conversion in Cr-based heterostructures is much lower compared to Pt-based equivalents.
Article
Materials Science, Multidisciplinary
Seungmo Yang, Tae-Seong Ju, Jeongwoo Seo, Kyoung-Woong Moon, Changsoo Kim, Hyun-Joong Kim, Jeonghun Shin, JungYup Yang, Chanyong Hwang, Jinpyo Hong
Summary: The introduction of a sandwiched synthetic antiferromagnetic frame, with reduced switching current and increased efficiency, provides a new avenue for designing future spintronic devices.
Article
Multidisciplinary Sciences
Min Gyu Kim, Andi Barbour, Wen Hu, Stuart B. Wilkins, Ian K. Robinson, Mark P. M. Dean, Junjie Yang, Choongjae Won, Sang-Wook Cheong, Claudio Mazzoli, Valery Kiryukhin
Summary: Magnetic domains in antiferromagnetic materials are crucial for understanding magnetism and its applications. In this study, videos of fluctuating antiferromagnetic domains in Ni2MnTeO6 were obtained using coherent x-ray diffraction. The findings highlight the potential significance of dynamic domain imaging in phase transition studies and magnetic device research.
Article
Nanoscience & Nanotechnology
Chao Zhou, Jia Xu, Tong Wu, Yizheng Wu
Summary: Antiferromagnets, with high stability and stray-field-free property, are considered as a promising host material for the next generation of magnetic storage. However, conventional magnetometry becomes ineffective in investigating their microscopic properties due to the absence of net magnetization. In this Perspective, an overview of various antiferromagnetic domain imaging techniques is provided, with a focus on the promising optical imaging method based on the magneto-optical birefringence effect. Recent advances in imaging antiferromagnetic domains using the magneto-optical birefringence technique are highlighted.
Article
Multidisciplinary Sciences
Sonka Reimers, Dominik Kriegner, Olena Gomonay, Dina Carbone, Filip Krizek, Vit Novak, Richard P. Campion, Francesco Maccherozzi, Alexander Bjorling, Oliver J. Amin, Luke X. Barton, Stuart F. Poole, Khalid A. Omari, Jan Michalicka, Ondrej Man, Jairo Sinova, Tomas Jungwirth, Peter Wadley, Sarnjeet S. Dhesi, Kevin W. Edmonds
Summary: This study reveals that the antiferromagnetic (AF) domain structure in CuMnAs thin films is dominated by nanoscale structural twin defects, which play a crucial role in determining the location and orientation of AF domain walls. The results provide insights into the interplay of crystalline defects, strain, and magnetic ordering in AF materials, offering a route to optimize device performance.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Libor Smejkal, Anna Birk Hellenes, Rafael Gonzalez-Hernandez, Jairo Sinova, Tomas Jungwirth
Summary: In this study, we propose that giant and tunneling magnetoresistance effects can be achieved in unconventional collinear antiferromagnets. We present archetype model mechanisms for these effects in multilayers composed of these unconventional collinear antiferromagnets and predict an approximately 100% scale for the effects based on first-principles calculations. We also highlight the ability of the alternating spin-momentum coupling to enable magnetic excitation by spin-transfer torque.
Article
Physics, Applied
M. J. Grzybowski, C. F. Schippers, M. E. Bal, K. Rubi, U. Zeitler, M. Foltyn, B. Koopmans, H. J. M. Swagten
Summary: One of the key challenges in antiferromagnetic spintronics is the detection of the Neel vector state. High current densities used in electrical switching experiments make it difficult to differentiate between magnetic and thermal origins of electrical signals. To address this, a study of temperature dependence in the switching experiment with CoO | Pt devices is presented. It is shown that a pattern of spin Hall magnetoresistance, indicative of the magnetic origin of the signal, can be extracted for current pulses below the Neel temperature. These findings are confirmed by additional experiments in an external magnetic field.
APPLIED PHYSICS LETTERS
(2022)
Article
Multidisciplinary Sciences
Filip Krizek, Sonka Reimers, Zdenek Kaspar, Alberto Marmodoro, Jan Michalicka, Ondrej Man, Alexander Edstrom, Oliver J. Amin, Kevin W. Edmonds, Richard P. Campion, Francesco Maccherozzi, Samjeet S. Dhesi, Jan Zubac, Dominik Kriegner, Dina Carbone, Jakub Zelezny, Karel Vyborny, Kamil Olejnik, Vit Novak, Jan Rusz, Juan-Carlos Idrobo, Peter Wadley, Tomas Jungwirth
Summary: This paper explores magnetic textures at the ultimate atomic scale in antiferromagnetic CuMnAs and achieves atomic resolution imaging using differential phase-contrast imaging within aberration-corrected scanning transmission electron microscopy. The study reveals abrupt domain walls corresponding to the Neel order reversal between neighboring atomic planes. The findings shed light on the development of electrical and ultrafast optical antiferromagnetic devices with magnetic field-insensitive neuromorphic functionalities.
Article
Physics, Applied
S. F. Poole, L. X. Barton, M. Wang, P. Manuel, D. Khalyavin, S. Langridge, K. W. Edmonds, R. P. Campion, V. Novak, P. Wadley
Summary: This study describes measurements of the uniaxial magnetic anisotropy and spin-flop rotation of the Neel vector in antiferromagnetic CuMnAs thin films using neutron diffraction. The experimental results indicate that films as thin as 20 nm undergo a spin-flop transition under magnetic fields, and neutron measurements can provide a quantitative determination of the spin-flop rotation throughout the antiferromagnet layer.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Multidisciplinary
R. D. Gonzalez Betancourt, J. Zubac, R. Gonzalez-Hernandez, K. Geishendorf, Z. Soban, G. Springholz, K. Olejnik, L. Smejkal, J. Sinova, T. Jungwirth, S. T. B. Goennenwein, A. Thomas, H. Reichlova, J. Zelezny, D. Kriegner
Summary: A spontaneous anomalous Hall signal was observed in an epitaxial film of MnTe, a semiconductor with collinear antiparallel magnetic ordering and zero net magnetization, even in the absence of an external magnetic field. The anomalous Hall effect originates from the unconventional phase with strong time-reversal symmetry breaking and alternating spin polarization. The anisotropic crystal environment of Mn atoms, caused by nonmagnetic Te atoms, plays a vital role in establishing the unconventional phase and generating the anomalous Hall effect.
PHYSICAL REVIEW LETTERS
(2023)
Correction
Engineering, Electrical & Electronic
Zexin Feng, Xiaorong Zhou, Libor Smejkal, Lei Wu, Zengwei Zhu, Huixin Guo, Rafael Gonzalez-Hernandez, Xiaoning Wang, Han Yan, Peixin Qin, Xin Zhang, Haojiang Wu, Hongyu Chen, Ziang Meng, Li Liu, Zhengcai Xia, Jairo Sinova, Tomas Jungwirth, Zhiqi Liu
NATURE ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
Zexin Feng, Xiaorong Zhou, Libor Smejkal, Lei Wu, Zengwei Zhu, Huixin Guo, Rafael Gonzalez-Hernandez, Xiaoning Wang, Han Yan, Peixin Qin, Xin Zhang, Haojiang Wu, Hongyu Chen, Ziang Meng, Li Liu, Zhengcai Xia, Jairo Sinova, Tomas Jungwirth, Zhiqi Liu
Summary: This study reports an anomalous Hall effect in collinear altermagnetic ruthenium dioxide, with an anomalous Hall conductivity exceeding 1,000 omega(-1) cm(-1). The phenomenon arises from an alternative magnetic phase in RuO2, characterized by alternating spin polarization in both real-space crystal structure and momentum-space band structure. The results could potentially lead to the exploration of topological Berry phases and dissipationless quantum transport in crystals of abundant elements and with a compensated antiparallel magnetic order.
NATURE ELECTRONICS
(2022)
Article
Materials Science, Multidisciplinary
A. Garrison Linn, Peipei Hao, Kyle N. Gordon, Dushyant Narayan, Bryan S. Berggren, Nathaniel Speiser, Sonka Reimers, Richard P. Campion, Vit Novak, Sarnjeet S. Dhesi, Timur K. Kim, Cephise Cacho, Libor Smejkal, Tomas Jungwirth, Jonathan D. Denlinger, Peter Wadley, Daniel S. Dessau
Summary: This study reports direct measurements of the electronic structure of tetragonal CuMnAs thin films using ARPES, including Fermi surfaces and energy-wavevector dispersions. After correcting for a chemical potential shift, there is excellent agreement between the experimental results and theoretical calculations. 2x1 surface reconstructions are also observed in low energy electron diffraction and ARPES. This work emphasizes the importance of controlling the chemical potential in tetragonal CuMnAs to explore and exploit tunable Dirac fermions.
NPJ QUANTUM MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
M. J. Grzybowski, C. F. Schippers, O. Gomonay, K. Rubi, M. E. Bal, U. Zeitler, A. Koziol-Rachwal, M. Szpytma, W. Janus, B. Kurowska, S. Kret, M. Gryglas-Borysiewicz, B. Koopmans, H. J. M. Swagten
Summary: Magnetocrystalline anisotropy in antiferromagnets is commonly considered constant, but our study on CoO shows that it actually depends on the magnetic field. This is demonstrated by the spin Hall magnetoresistance of the CoO|Pt device. We observe a spin-flop transition at 240 K at 7.0 T, and unexpected hysteresis in the angular dependence of magnetoresistance persists up to 30 T, indicating the presence of unquenched orbital momentum that plays a crucial role in antiferromagnetic spintronics.
Article
Materials Science, Multidisciplinary
C. F. Schippers, M. J. Grzybowski, K. Rubi, M. E. Bal, T. J. Kools, R. A. Duine, U. Zeitler, H. J. M. Swagten
Summary: Recent demonstrations have shown the electrical switching of antiferromagnets (AFs), which has greatly impacted the field of AF spintronics. However, various nonmagnetic effects make it difficult to distinguish them from actual magnetic effects. In this study, we investigated the electrical switching of NiO films in Pt/NiO devices with magnetic fields up to 15 T to quantitatively separate these magnetic and nonmagnetic effects. Our results indicate that these magnetic fields suppress the magnetic components of NiO's electrical switching while preserving the nonmagnetic components. By using a monodomainization model, we were able to separate and analyze the contributions of these effects, revealing their behaviors with respect to current density. These findings highlight the importance of combining electrical methods and strong magnetic fields in AF spintronics research.
