Phase coherent transport in bilayer and trilayer MoS2

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 trilayer MoS2. We observe a similar crossover from weak localization to weak antilocalization, 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 the D' yakonov-Perel mechanism is dominant in all devices despite the centrosymmetry of the bilayer device. 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.