Weak-localization (WL) measurements were performed in a Bi cluster-decorated graphene sheet. The charge concentration was kept constant, and the amplitude of the conductance correction was suppressed after the Bi-cluster deposition. Detailed WL data were obtained while the gate and temperature were changed. Using E. McCann's formula, the spin-relaxation time was extracted, which was found to increase with the elastic scattering time. This is attributed to the Elliott-Yafet spin relaxation and Kane-Mele type spin-orbit coupling (SOC). The SOC strength was enhanced to 2.64 meV as a result of the first deposition. The coverage effect is discussed according to the measurement after the second deposition.

No abstract

In order to enhance the spin orbit interaction (SOI) in graphene for seeking the dissipationless quantum spin Hall devices, unique Kane-Mele-type SOI and high mobility samples are desired. However, the common external modification of graphene often introduces “extrinsic” Rashba-type SOI, which will destroy the possible topological state, bring a certain degree of impurity scattering and reduce the sample mobility. Here we show that by the EDTA-Dy molecule dressing, the Kane-Mele type SOI is mimicked, indicating that the carrier mobility is even improved. It is evidenced by the suppressed weak localization at equal carrier densities and simultaneous Elliot-Yafet spin relaxation. The extracted spin scattering time is monotonically dependent on the carrier elastic scattering time. The improved quantum Hall plateaus can be seen even after the external operation. This is attributed to the spin-flexural phonon coupling induced by the enhanced graphene ripples as revealed by the in-plane magnetotransport measurement.