Nonlinear balance equations for hot-electron transport with finite phonon-relaxation time

Spin–orbit coupling induced magnetoresistance oscillation in a dc biased two-dimensional electron system

We study dc-current effects on the magnetoresistance oscillation in a two-dimensional electron gas with Rashba spin-orbit coupling, using the balance-equation approach to nonlinear magnetotransport. In the weak current limit the magnetoresistance exhibits periodical Shubnikov-de Haas oscillation with changing Rashba coupling strength for a fixed magnetic field. At finite dc bias, the period of the oscillation halves when the interbranch contribution to resistivity dominates. With further increasing current density, the oscillatory resistivity exhibits phase inversion, i.e., magnetoresistivity minima (maxima) invert to maxima (minima) at certain values of the dc bias, which is due to the current-induced magnetoresistance oscillation.

Thermoelectric power in graphene

Considering electron-impurity and electron-phonon scattering, we present a balance-equation-based theoretical examination of thermoelectric power (TEP) in a two-dimensional single-layer graphene away from the carrier neutrality point. Both the boundary scattering and phonon-phonon interaction in phonon relaxation processes are taken into account. We find that, at temperatures T > 10 K, the contribution to TEP mainly comes from diffusive processes and the phonon-drag effect can be ignored. However, at T ≤ 10 K, the phonon-phonon interaction leads to a phonon-drag peak in the temperature dependence of TEP. We also compare our results with experiments.