Novel energy scale in the interacting two-dimensional electron system evidenced from transport and thermodynamic measurements
We study how the non-Fermi-liquid two-phase state reveals itself in transport properties of high-mobility Si-MOSFETs. We have found features in zero-field transport, magnetotransport, and thermodynamic spin magnetization in a 2D correlated electron system that may be directly related with the two-phase state. The features manifest above a density-dependent temperature T* that represents a high-energy scale, apart from the Fermi energy. More specifically, inmagnetoconductivity, we found a sharp onset of the regime delta sigma (B, T)alpha(B/T)(2) above a density-dependent temperature T-kink(n), a high-energy behavior that "mimics" the low-temperature diffusive interaction regime. The zero-field resistivity temperature dependence exhibits an inflection point T-infl(n). In thermodynamic magnetization, the weak-field spin susceptibility per electron partial derivative chi/partial derivative n changes sign at T-dM/dn (n). All three notable temperatures, T-kink, T-infl,T- and T-dM/dn behave critically alpha(n - n(c)), are close to each other, and are intrinsic to high-mobility samples solely; we therefore associate them with an energy scale T* caused by interactions in the 2DE system.