Spin Accumulation and Dynamics in Inversion-Symmetric van der Waals Crystals

• Published in: Physical review letters Vol. 120; no. 26; p. 266801
• Main Authors: Guimarães, M H D, Koopmans, B
• Format: Journal Article
• Language: English
• Published: United States 29.06.2018
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.120.266801

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 WSe_{2} and MoSe_{2} bulk crystals to study this spin-layer polarization and unveil its dynamics. Our measurements show that the spin-layer relaxation time in WSe_{2} is limited by phonon scattering at high temperatures and that the interlayer hopping can be tuned by a small in-plane magnetic field at low temperatures, enhancing the relaxation rates. We find a significantly lower lifetime for MoSe_{2} which agrees with theoretical expectations of a spin-layer polarization stabilized by the larger spin-orbit coupling in WSe_{2}.