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@INPROCEEDINGS{Freimuth:834127,
author = {Freimuth, Frank},
title = {{T}hermal and electrical spin-orbit torques in collinear
and noncollinear magnets},
reportid = {FZJ-2017-04126},
year = {2017},
abstract = {While spin-orbit torques [1] in magnetic bilayers composed
of a 5d transition metal layer and a ferromagnetic layer can
serve as a competitive alternative to the Slonczewski
spin-transfer torque in spin-valves and magnetic tunnel
junctions in order to realize MRAM devices, spin-orbit
torques have even more potential, and are a potential
game-changer, in antiferromagnetic spintronics [2] and in
noncollinear magnets. After discussing the theory of thermal
and electrical spin-orbit torques in collinear magnets, we
will shift the focus to current-induced torques and
spin-orbit driven effects in noncollinear magnetic bilayers.
The combination of structural inversion asymmetry present in
the bilayer geometry with noncollinear magnetism leads to
several additional spin-orbit driven effects, such as the
Dzyaloshinskii-Moriya interaction [3,4,5,6] and chiral
damping [7], which join the other effects and
current-induced torques important in noncollinear magnets
and magnetic bilayers, such as spin-transfer torque,
spin-orbit torque and nonadiabatic torque. In particular the
combined action of the Dzyaloshinskii-Moriya interaction and
the spin-orbit torque from the spin Hall effect enables
current-driven domain-wall motion at ultrahigh speeds [8,9].
The large number of current-induced torques and spin-orbit
driven effects participating in the current-induced motion
of domain-walls or skyrmions are difficult to disentangle
and to quantify in experimental measurements.
First-principles density functional theory is an ideal tool
to understand and to quantify these effects. For this
purpose we extend our computational formalism of spin-orbit
torques [10,11,12] to noncollinear magnets. An important
problem in the formalism development concerns the correct
inclusion of vertex corrections, without which several
components of the current-induced torques in noncollinear
chiral magnets would violate conservation laws. We will
discuss the current-induced torques and spin-orbit driven
effects that arise from the combination of structural
inversion asymmetry, spin-orbit coupling, and noncollinear
magnetism in Co/Pt and Mn/W bilayer systems. References: [1]
K. Garello et al., Nature Nanotechnology 8, 587 (2013), [2]
P. Wadley et al., Science 351, 587 (2016), [3] F. Freimuth
et al., JPCM 26, 104202 (2014), [4] F. Freimuth et al., PRB
88, 214409 (2013), [5] F. Freimuth et al., JPCM 28, 316001
(2016), [6] F. Freimuth et al., ArXiv e-prints (2016),
1610.06541, [7] E. Jue et al., Nature Materials 15, 272
(2016), [8] L. Thomas et al., Nature Nanotechnology 8, 527
(2013), [9] S. Emori et al., Nature Materials 12, 611
(2013), [10] F. Freimuth et al., PRB 92, 064415 (2015), [11]
F. Freimuth et al., PRB 90, 174423 (2014), [12] G. Geranton
et al., PRB 91, 014417 (2015)},
month = {Jun},
date = {2017-06-12},
organization = {Spincaloritronics VIII, Regensburg
(Germany), 12 Jun 2017 - 15 Jun 2017},
subtyp = {Invited},
cin = {IAS-1 / PGI-1 / JARA-FIT / JARA-HPC},
cid = {I:(DE-Juel1)IAS-1-20090406 / I:(DE-Juel1)PGI-1-20110106 /
$I:(DE-82)080009_20140620$ / $I:(DE-82)080012_20140620$},
pnm = {142 - Controlling Spin-Based Phenomena (POF3-142)},
pid = {G:(DE-HGF)POF3-142},
typ = {PUB:(DE-HGF)6},
url = {https://juser.fz-juelich.de/record/834127},
}