Inversion symmetric materials are forbidden to show an overall spin texture in their band structure in the presence of time-reversal symmetry. However, in van der Waals materials which lack inversion symmetry within a single layer, it has been proposed that a layer-dependent spin texture can arise leading to a coupled spin-layer degree of freedom. Here we use time-resolved Kerr rotation in inversion symmetric WSe2 and MoSe2 bulk crystals to study this spin-layer polarization and unveil its dynamics. Our measurements show that the spin-layer relaxation time in WSe2 is limited by phonon-scattering at high temperatures and that the inter-layer hopping can be tunned by a small in-plane magnetic field at low temperatures, enhancing the relaxation rates. We find a significantly lower lifetime for MoSe2 which agrees with theoretical expectations of a spin-layer polarization stabilized by the larger spin-orbit coupling in WSe2.
@article{arxiv.1806.02558,
title = {Spin accumulation and dynamics in inversion-symmetric van der Waals crystals},
author = {M. H. D. Guimaraes and B. Koopmans},
journal= {arXiv preprint arXiv:1806.02558},
year = {2018}
}