Novel Energy Scale in the Interacting 2D Electron System Evidenced from Transport and Thermodynamic Measurements

Abstract

By analyzing the in-plane field magnetoconductivity, zero field transport, and thermodynamic spin magnetization in 2D correlated electron system in high mobility Si-MOS samples, we have revealed a novel high energy scale $T^{\ast }$, beyond the Fermi energy. In magnetoconductivity, we found a sharp onset of the novel regime $\delta \sigma (B,T)\propto (B/T{)}^2$ above a density dependent temperature $T_{\mathrm{kink}}(n)$, the high-energy behavior that "mimics" the low-temperature diffusive interaction regime. The zero field resistivity temperature dependence exhibits an inflection point $T_{\mathrm{infl}}$. In thermodynamic magnetization, the weak field spin susceptibility per electron, $\partial \chi /\partial n$ changes sign at $T_{dM/dn}$. All three notable temperatures, $T_{\mathrm{kink}}$, $T_{\mathrm{infl}}$, and $T_{dM/dn}$, behave critically $\propto (n-n_c)$, are close to each other, and are intrinsic to high mobility samples only; we therefore associate them with a novel energy scale $T^{\ast }$ caused by interactions in the 2DE system.