ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium

feb. 25. péntek 10h15,

online
<https://teams.microsoft.com/l/meetup-join/19%3ae1a26210676841cdbb27bb01cf353392%40thread.tacv2/1645441200945?context=%7b%22Tid%22%3a%226a3548ab-7570-4271-91a8-58da00697029%22%2c%22Oid%22%3a%22c7eaf7d2-684b-4597-b217-6a9121400219%22%7d>
a Microsoft Teamsben,

Jakub Zelezny (Institute of Physics of the Czech Academy of Sciences):

Spin-transfer torque in non-collinear antiferromagnetic junctions

Ferromagnetic spin-valves and tunneling junctions are among the most
fundamental and important spintronics devices. Their functionality is based
on two effects: the giant or tunneling magnetoresistance for electrical
readout and the spin-transfer torque allowing for electrical switching. It
has been predicted that the same functionality could be achieved with
antiferromagnetic junctions, which would provide various advantages over
ferromagnets, such as a much faster switching speed. However, these devices
are very sensitive to disorder and have never been experimentally
demonstrated [1].

Here we show that the key to obtaining robust spin-transfer torque and
magnetoresistance in antiferromagnets is utilizing lower symmetry
antiferromagnets, in which electrical current is spin-polarized [2]. We
consider junctions composed of non-collinear antiferromagnets and find a
spin-transfer torque and magnetoresistance with a magnitude and robustness
against disorder comparable to ferromagnetic junctions [3]. Furthermore,
our calculations reveal novel aspects of the torque in non-collinear
junctions. In particular, we find that apart from the conventional
spin-transfer torque, a novel self-generated torque appears. This torque is
similar to a spin-orbit torque but has a non-relativistic origin. We also
find that a torque appears for any configuration of the junction, in
contrast to ferromagnetic junctions where the torque vanishes in the
parallel or antiparallel configurations.

[1] J. Železný et al., Nature Physics 14, 220–228 (2018)
[2] J. Železný et al., Phys. Rev. Lett. 119, 187204 (2017)
[3] S. Ghosh et al., arXiv:2109.01399 (2021)

Minden érdeklődőt szeretettel várunk,
 Asbóth János
  szemináriumi koordinátor