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

TL;DR

This study uncovers a new high energy scale $T^*$ in 2D electron systems, evidenced through transport and thermodynamic measurements, indicating interaction-driven phenomena beyond the Fermi energy.

Contribution

The paper identifies and characterizes a novel high energy scale $T^*$ in 2D correlated electron systems, revealed through multiple experimental techniques and critical behavior analysis.

Findings

Discovery of a high energy scale $T^*$ in 2D electron systems.

Identification of three correlated temperature scales: $T_{kink}$, $T_{infl}$, and $T_{dM/dn}$.

All three scales exhibit critical behavior proportional to $(n - n_c)$.

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 $T^*$, 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 $T_{\rm kink}(n)$, the high-energy behavior that "mimics" the low-temperature diffusive interaction regime. The zero field resistivity temperature dependence exhibits an inflection point $T_{\rm infl}$. In thermodynamic magnetization, the weak field spin susceptibility per electron, $\partial \chi /\partial n$ changes sign at $T_{dM/d n}$. All three notable temperatures, $T_{\rm kink}$, $T_{\rm infl}$, and $T_{d M/ d n}$, 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 $T^*$ caused by interactions in the 2DE system.