Phase coherent transport in bilayer and trilayer MoS2

TL;DR

This study investigates phase-coherent transport in mono-, bi-, and tri-layer MoS2, revealing dominant D'yakonov-Perel spin relaxation mechanism and no electric-field induced changes in spin-orbit coupling, indicating weak interlayer coupling.

Contribution

It provides experimental insights into spin relaxation mechanisms and electric field effects in multilayer MoS2, showing multilayers behave like decoupled monolayers.

Findings

Spin relaxation time inversely proportional to momentum relaxation time.

No electric-field induced change in spin-orbit coupling.

Multilayer MoS2 behaves as decoupled monolayers.

Abstract

Bilayer MoS2 is a centrosymmetric semiconductor with degenerate spin states in the six valleys at the corners of the Brillouin zone. It has been proposed that breaking of this inversion symmetry by an out-of-plane electric field breaks this degeneracy, allowing for spin and valley lifetimes to be manipulated electrically in bilayer MoS2 with an electric field. In this work, we report phase-coherent transport properties of double-gated mono-, bi-, and tri-layer MoS2. We observe a similar crossover from weak localization to weak anti-localization, from which we extract the spin relaxation time as a function of both electric field and temperature. We find that the spin relaxation time is inversely proportional to momentum relaxation time, indicating that D'yakonov-Perel mechanism is dominant in all devices despite its centrosymmetry. Further, we found no evidence of electric-field induced changes in spin-orbit coupling strength. This suggests that the interlayer coupling is sufficiently weak and that electron-doped dichalcogenide multilayers behave electrically as decoupled monolayers.