Critical behaviour of the conductivity in metallic n-type InP close to the metal-insulator transition

Publisher Website
Google Scholar
Abstract
The metal-insulator transition (MIT) induced by a magnetic field in barely metallic and compensated n-type InP has been re-examined. Using a new analysis methods, the authors have determined the magnetic field for which the conductivity changes from a metallic behaviour to a variable-range hopping regime. On the metallic side of the MIT, the electrical conductivity is found to obey sigma = sigma 0+mTs down to 60 mK; the zero-temperature conductivity can be described by a scaling law with an exponent nu =1 and there is no evidence for a minimum metallic conductivity. As the MIT is approached, they observe a clear crossover from a T1/2 to T1/3 temperature dependence of the conductivity, which is related to a competition between two length scales: the correlation length and the interaction length.