Temperature effects on edge-state properties in the integer quantum Hall regime

Abstract

The edge and bulk structure of Landau levels (LLs) in a wide channel at the $ ν=1$ quantum Hall regime is calculated for not-too-low temperatures, $\hbar ω_{c} \gg k_{B}T\gg \hbar v_{g}/2\ell_{0}$, where $v_{g}$ is the group velocity of the edge states and $\ell_{0}=\sqrt{\hbar c/|e|B}$ is the magnetic length. Edge-states correlations essentially modify the spatial behavior of the lowest spin-up LL, which is occupied, compared to the lowest spin-down LL, which is empty. The influence of many-body interactions on the spatially inhomogeneous spin-splitting between the two lowest LLs is studied within the generalized local density approximation. Temperature effects on the enhanced spin-splitting, the position of the Fermi level within the exchange enhanced gap and the renormalization of edge-states group velocity by edge states screening are considered. It is shown that the maximum activation energy $G$ in the bulk of the channel is determined by the gap between the Fermi level and the bottom of the spin-down LL, because the gap between the Fermi level and the spin-up LL is much larger. For the maximum value of $G$, it is shown that the renormalized group velocity $v_{g}\propto T$ for $T\to 0$ and, in particular, the condition of not-too-low $T$ can be satisfied for $4.2\agt T\agt0.3$ K. In other words, the regime of not-too-low temperatures regime can be achieved even for rather low $T$.