Resonances in dynamical spin-current susceptibilities in spin-orbit coupled Graphene

It was recently shown that graphene grown on transition metal dichalcogenides hosts spin resonances in the absence of any external magnetic field due to the interplay of electronic correlations with the Rashba and Valley-Zeeman types of spin-orbit couplings (SOC). These resonances are due to oscillations of magnetization and staggered magnetization (defined as the difference in magnetic moment densities between the two valleys). Because the SOC breaks parity, these spin resonances show up in optical conductivity (where current is driven by an electric field) in addition to the usual magnetic susceptibility (where magnetization is driven by a magnetic field). In this work, we identify two additional unconventional dynamical responses that are sensitive to these resonances: one is a current that is driven by the magnetic field and the other is a magnetization that is driven by the electric field. These cross spin-current susceptibilities capture the dynamical version of the Edelstein and inverse-Edelstein effect known in 2D electron gases (2DEG). We compare the results in graphene with those of the 2DEG and highlight the role of Rashba vs Valley Zeeman SOCs in such responses.