Metal-insulator transitions in the kondo insulator FeSi and classic semiconductors are similar

J. F. DiTusa, Louisiana State University
K. Friemelt, Universität Konstanz
E. Bucher, Universität Konstanz
G. Aeppli, NEC Laboratories America, Inc.
A. P. Ramirez, Nokia Bell Labs


We have observed the metal-insulator transition in the strongly correlated insulator FeSi with the chemical substitution of Al at the Si site. The magnetic susceptibility, heat capacity, and field-dependent conductivity are measured for Al concentrations ranging from 0 to 0.08. For concentrations ≤ 0.01 we find metallic properties quantitatively similar to those measured in Si:P with the exception of a greatly enhanced quasiparticle mass. Below 2 K the temperature and field-dependent conductivity can be completely described by the theory of disordered Fermi liquids. © 1997 The American Physical Society.