Fyzikální ústav Akademie věd ČR

Seminář Úterý, 28.02.2017 15:00 - 16:00

Přednášející: Libor Šmejkal (Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, CZ-16253 Praha 6 Institut für Physik, Johannes Gutenberg Universität Mainz, D-55099 Mainz, Germany Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2)
Místo: Na Slovance, přednáškový sál v přízemí
Jazyk: anglicky
Pořadatelé: Oddělení teorie kondenzovaných látek

Abstract: Merging topology with magnetism is rapidly becoming a new direction in the field of topological quantum materials boosted by the recent discoveries of Dirac and Weyl fermions. However, merits of the spin-momentum locked Dirac quasiparticles of topological insulators did not reach its full potential for spintronics due to the practical (low temperatures and bulk doping problem) as well as fundamental limitations (challenging symmetry and dimensional compatibilities). Recent prediction of the interplay between Néel spin-orbit torque and Dirac quasiparticles in an antiferromagnet (AF) [1] indicates AFs might become the leading magnets on the route towards topological spintronics.
In this talk, we will review the latest developments in the fields of topological quantum matter and spintronics. We will show that the incompatibility of topological Dirac quasiparticles with (ferro)magnetism can be overcome in AFs due to their effective time reversal and nonsymmorphic crystalline symmetries. We will formulate the generic symmetry criteria for Dirac semimetals in AFs, as parent phases for Weyl semimetals and topological insulators.
In the second part, we will illustrate how to achieve the fundamental limits of the magnetotransport and spintronics effects in the recently identified topological AFs (e.g. CuMnAs)[1] from the perspective of the first-principle electronic structure theory. We will focus on the novel effects: topological metal-insulator transition and anisotropic magnetoresistance.[1] Finally, we will discuss experimental designs for the observation of the proposed effects, e.g. magnetically induced Weyl semimetal state.

[1] L.Šmejkal, J.Železný, J.Sinova, T.Jungwirth, arXiv:1610.08107 (2016)