"Spin-orbit coupling studies of materials: some examples"

Who: Dr. Roberto Robles, ICN2

Place: Donostia International Physics Center

Date: Friday, 20 April 2018, 12:00

Spin-orbit coupling (SOC) plays a central role in the properties of many tech-
nologically and fundamentally relevant materials. In the last years di erent
phenomena have been predicted and discovered involving SOC. For example,
SOC is crucial in the study of exotic magnetic properties, spintronics, and
topological insulators.

One of the most commonly studied consequences of SOC is the preferen-
tial orientation of the magnetic moments along certain directions of the
lattice: the magnetic anisotropy energy (MAE). We have studied MAE in
low-dimensional systems consisting of heterogeneous transition metal chains
supported on a Cu2N/Cu(100) surface [1]. MAE is also relevant in the study
of materials for magnetic data storage. Conventionally these devices are
controlled by magnetic elds generated by electric currents. To optimize
the energy efficiency it is desirable to lower the magnetic elds needed to
manipulate the devices. This can be achieved by lowering the coercivity of
the material. Here we show the reduction of the coercivity in nanoporous
Cu-Ni lms just by the action of an electric eld. By performing ab-initio
calculations we o er some insight into the mechanisms behind the observed
behavior [2].

Another interesting topic is the enhancement of spin-orbit interactions in
materials with small intrinsic SOC, like graphene. One way of achieving this
goal is the proximity with a material with strong intrinsic SOC, such as topo-
logical insulators. We have studied the spin properties of Graphene/Bi2Se3
heterostructures, in particular the nontrivial spin-texture induced in the
graphene states, and their possible implications on the spin transport prop-
erties of the resulting system [3].

Finally, I will comment on recent advances of the treatment of SOC in the
ab-initio DFT code Siesta.

[1] D-J. Choi et al. Physical Review B 94, 085406 (2016)
[2] A. Quintana et al. Advanced Functional Materials 27, 1701904 (2017)
[3] K. Song et al. Nano Letters 18, 2033 (2018)

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