Antiferromagneten für spinorbitronics durch ab-initio Theorie
Zusammenfassung der Projektergebnisse
The momentum of antiferromagnetic spintronics as a distinct promising branch of spintronics was rapidly rising in the past years. Some of the major practical issues associated with implementation of antiferromagnets (AFMs) into existing and novel device paradigms root in advancing our ability to detect antiferromagnetic order, track corresponding dynamics, and exploit the complexity of antiferromagnetism for the benefits of technology. With this project we have addressed and developed several corresponding core aspects directly related to the interaction of AFM order with external fields and novel aspects of antiferromagnetism which bare significant practical potential. The initial plan for the project activity evolved around relativistic coupling of currents and magnetization in AFM heterostructures for the design, understanding and discovery of novel relativistic effects which manifest in Hall effects, spin-orbit torques, AFM dynamics, non-trivial chiral response of AFMs, as well as emergent orbital magnetism and exchange interactions. By referring to microscopic models and ab-initio techniques we have made significant progress along the objectives of the project outlined above. We have scrutinized in detail various types of spin-orbit torques which can appear in AFM materials and provided the conditions for their effectiveness in terms of switching the AFM order. We have discovered that the long-range AFM interaction can acquire a “chiral” flavor in the context of a new type of antisymmetric interaction – the long-range interlayer Dzyaloshinskii-Moriya interaction, which we have shown to emerge in AFM coupled magnetic multilayers. We have considered various families of AFM materials and studied corresponding Hall effects, discovering that while the anomalous Hall effect and magneto-optical effects in Mn3X type of compounds can be used to detect the details of spin distribution, the peculiarities of the anomalous Hall effect here also open a road for an implementation of AFMs into the setup of spincaloritronics as equal partners to ferromagnets. We have uncovered that complex AFM order characterized with non-zero scalar spin chirality gives rise to so-called topological orbital magnetism in 3D AFMs, demonstrating on an example of specific material candidates that this effect goes hand in hand with the novel discovered type of phenomena named the topological magneto-optical effects, which can be utilized to efficiently detect the complex AFM order optically. A recent unexpected twist in the field was a rapid progress in the domain of so-called topological antiferromagnetic spintronics, where we have made significant advances as well. In the realm of insulating topologically complex AFMs we have uncovered the emergence of so-called quantum topological magnetooptical effect which paves the way to realization of exotic topological phases of AFM materials. Several AFM materials candidates were suggested to exhibit novel flavors of topology in the reciprocal space, such as two-dimensional non-symmorphic AFM topological insulator phase and hybrid quantum anomalous Hall state. Finally, new types of Berry phases were shown to dominate the chiral response of AFM to applied fields in terms of the so-called chiral Hall effect. Overall, we believe that the activities ignited and executed in the course of the project have been very beneficial for the field of antiferromagnetic spintronics, especially in the context of advancing our ability to treat and design various non-equilibrium effects taking place in AFMs from quantum mechanical microscopic theory. Some of the studied and discovered in the project effects bare a strong direct potential for practical applications in terms of e.g. shaping new types of AFM order and new ways of AFM order and dynamics detection. For executing the objectives of the project several fruitful collaborations have been initiated, and the involvement and promotion of your researchers centered around this project has been also significant.
Projektbezogene Publikationen (Auswahl)
- “Topological Antiferromagnetic Spintronics”, Nature Physics 14, 242 (2018)
L. Smejkal, Y. Mokrousov, B. Yan, A. H. MacDonald
(Siehe online unter https://doi.org/10.1038/s41567-018-0064-5) - “Long-range Chiral Exchange Interaction in Synthetic Antiferromagnets”, Nature Materials 18, 703 (2019)
D.-S. Han, K. Lee, J.-P. Hanke, Y. Mokrousov, K.-W. Kim, W. Yoo, Y. L. W. van Hees, T.-W. Kim, R. Lavrijsen, C.-Y. You, H. J. M. Swagten, M.-H. Jung, M. Kläui
(Siehe online unter https://doi.org/10.1038/s41563-019-0370-z) - “The Chiral Hall Effect in Canted Ferromagnets and Antiferromagnets” (2020)
J. Kipp, K. Samanta, F. Lux, M. Merte, J.-P. Hanke, M. Redies, F. Freimuth, S. Blügel, M. Lezaic, and Y. Mokrousov
(Siehe online unter https://doi.org/10.1038/s42005-021-00587-3) - „Antiferromagnetic Topological Insulator with Nonsymmorphic Protection in Two Dimensions”, Physical Review Letters 124, 066401 (2020)
C. Niu, H. Wang, N. Mao, B. Huang, Y. Mokrousov, Y. Dai
(Siehe online unter https://doi.org/10.1103/physrevlett.124.066401) - „Topological Magneto-Optical Effects and Their Quantization in Noncoplanar Antiferromagnets”, Nature Communications 11, 118 (2020)
W. Feng, J.-P. Hanke, X. Zhou, G.-Y. Guo, S. Blügel, Y. Mokrousov, Y. Yao
(Siehe online unter https://doi.org/10.1038/s41467-019-13968-8) - „Topological-chiral magnetic interactions driven by emergent orbital magnetism”, Nature Communications 11, 511 (2020)
S. Grytsiuk, J.-P. Hanke, M. Hoffmann, J. Bouaziz, O. Gomonay, G. Bihlmayer, S. Lounis, Y. Mokrousov, S. Blügel
(Siehe online unter https://doi.org/10.1038/s41467-019-14030-3)
