SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 41: Focus Session: Altermagnetism: Transport, Optics, Excitations
MA 41.4: Vortrag
Donnerstag, 30. März 2023, 16:15–16:30, HSZ 02
Giant magnetoresistance effects in altermagnets — •Anna Birk Hellenes1, Rafael González-Hernández2, Jairo Sinova1,3, Tomas Jungwirth3,4, and Libor Šmejkal1,3 — 1Johannes Gutenberg Universität Mainz, Germany — 2Universidad del Norte, Barranquilla, Colombia — 3Czech Academy of Sciences, Prague, Czech Republic — 4University of Nottingham, United Kingdom
Commercial spintronics devices using magnetoresistance effects rely on spin currents in ferromagnets, generated by a time-reversal symmetry broken band structure. To realise a counterpart effect with all-antiferromagnetic electrodes has remained experimentally elusive, as the combined time-reversal symmetry with translation or inversion in antiferromagnets prohibits nonrelativistic spin polarisation. Recently, a third fundamental magnetic order was discovered, which exhibits exclusively different spin symmetries from ferromagnets and antiferromagnets[1]. In these altermagnets, the spin polarisation forms d,g, or i-wave compensated spin order in momentum space which breaks time-reversal symmetry. Hence, altermagnetism provides a unifying explanation for our recently predicted giant TMR and GMR effects[2,3]. In the present contribution, we describe the symmetry requirements that lead to distinct spin polarisations such as the d-wave type, and illustrate the GMR and TMR mechanism with tight-binding models and in the candidate materials RuO2 and Mn5Si3. [1] L. Šmejkal et al., Phys. Rev. X 12, 031042, 2022. [2] L. Šmejkal, A. B. Hellenes et al., Phys. Rev. X 12, 011028, 2022. [3] H. Reichlova et al., arXiv:2012.15651v2.