Temperature-induced break up of strongly correlated electron state in InSb

Abstract

We report the observation of a temperature-induced transition in highly compensated n-InSb with n=3×10 14 cm −3 . The temperature dependence of conductivity shows the metal-like behavior ( σ∝ T 1/2) at temperatures above the critical T 0=0.25 K . The transition was detected as a crossover to the hopping transport at T< T 0. As we suppose, the thermal length L T=(2π Dℏ/ k B T) 1/2 rises with decreasing temperature and reaches the correlation length determined by disorder ( D is the electron diffusion coefficient). At T< T 0, electrons become correlated. k B T 0 is approximately the Coulomb energy. In other words, thermal energy should be less than the energy of fluctuations considered by Anderson or Lifshits models.