Seminarium Fizyki Ciała Stałego

Hexagonal MnTe is an antiferromagnetic semiconductor, known from the 1960's [1-7]. Being recentlyclassified as an altermagnet [8], it experiences a renaissance of scientific interest, e.g. [9-13]. One ofthe reasons it attracts so much attention is that MnTe is one of the few conducting altermagnets,opening the possibilities to probe the relations between its (antiferro)magnetic state and transportproperties, key aspects for spin-based memories and spintronic applications. In this seminar I will discuss the properties of bulk MnTe crystals. I will cover the investigations of theresistivity tensor (revealing anomalous Hall effect), combined with magnetization studies (revealingweak ferromagnetism). Explanations of these effects are proposed, basing on Dzyaloshinskii-Moriyainteraction and non-vanishing Berry curvature. The role of non-relativistic effects (underlyingaltermagnetism) and relativistic ones will be discussed. [1] T. Komatsubara, M. Murakami, and E. Hirahara,Magnetic properties of manganese telluride singlecrystals, J. Phys. Soc. Jpn. 18, 356 (1963). [2] J. Wasscher, Evidence of weak ferromagnetism inMnTe from galvanomagnetic measurements, Solid StateCommun. 3, 169 (1965). [3] F. E. Maranzana, Contributions to the theory of theanomalous Hall effect in ferro- and antiferromagneticmaterials, Phys. Rev. 160, 421 (1967). [4] J. W. Allen, G. Lucovsky, and J. C. Mikkelsen, Opticalproperties and electronic structure of crossroads materialMnTe, Solid State Commun. 24, 367 (1977). [5] W. Szuszkiewicz, E. Dynowska, B. Witkowska, and B.Hennion, Spin-wave measurements on hexagonal MnTeof NiAs-type structure by inelastic neutron scattering,Phys. Rev. B 73, 104403 (2006). [6] E. Przezdziecka, E. Kaminska, E. Dynowska, R. Butkute,W. Dobrowolski, H. Kepa, R. Jakiela, M. Aleszkiewicz, E.Lusakowska, E. Janik, and J. Kossut, Preparation andcharacterization of hexagonal MnTe and ZnO layers, Phys.Status Solidi C 2, 1218 (2005). [7] D. Kriegner, K. Výborný, K. Olejník, H. Reichlová, V.Novák, X. Marti, J. Gazquez, V. Saidl, P. Nˇemec, V. V.Volobuev, G. Springholz, V. Holý, and T. Jungwirth,Multiple-stable anisotropic magnetoresistance memoryin antiferromagnetic MnTe, Nat. Commun. 7, 11623(2016). [8] L. Šmejkal, J. Sinova, and T. Jungwirth, Beyondconventional ferromagnetism and antiferromagnetism: Aphase with nonrelativistic spin and crystal rotationsymmetry, Phys. Rev. X 12, 031042 (2022). [9] K. P. Kluczyk, K. Gas, M. J. Grzybowski , P. Skupiński, M.A. Borysiewicz, T. Fas , J. Suffczyński , J. Z. Domagala , K.Grasza, A. Mycielski, M. Baj, K. H. Ahn, K. Výborný, M.Sawicki, M. Gryglas-Borysiewicz, Coexistence ofanomalous Hall effect and weak magnetization in anominally collinear antiferromagnet MnTe, Phys. Rev. B110, 15520 (2024), [10] J. Krempaský, L. Šmejkal, S. W. D’Souza, M. Hajlaoui,G. Springholz, K. Uhlíˇrová, F. Alarab, P. C. Constantinou,V. Strocov, D. Usanov, W. R. Pudelko, R. González-Hernández, A. Birk Hellenes, Z. Jansa, H. Reichlová, Z.Šobáˇn, R. D. Gonzalez Betancourt, P. Wadley, J. Sinova,D. Kriegner et al., Altermagnetic lifting of Kramers spindegeneracy, Nature 626, 517 (2024). [11] J. Dzian, P. Kubaščík, S. Tázlarů, M. Białek, M. Šindler,F. Le Mardelé, C. Kadlec, F. Kadlec, M. Gryglas-Borysiewicz, K. P. Kluczyk, A. Mycielski, P. Skupiński, J.Hejtmánek, R. Tesař, J. Železný, A. -L. Barra, C. Faugeras,J. Volný, K. Uhlířová, L. Nádvorník, M. Veis, K. Výborný,and M. Orlita, Antiferromagnetic resonance in