2000/08/08 by Michio Watanabe
Physics and Astronomy · #cond-mat.dis-nn
published as In "Phase Transitions and Self-Organization in Electronic and Molecular Materials", edited by J. C. Phillips and M. F. Thorpe (Kluwer Academic/Plenum Publishers, New York, 2001, ISBN 0-306-46568-X) pp. 291--310 · LaTeX2e, 21 pages with 15 embedded figures, to be published in M. F. Thorpe and J. C. Phillips (eds.), "Phase Transitions and Self-Organization in Electronic and Molecular Materials" (Kluwer Academic/Plenum Publishers)
arxiv created 2000/08/08 · arxiv updated 2009/11/30
We have measured the electrical conductivity of Ge:Ga samples prepared by neutron-transmutation doping of isotopically enriched 70Ge single crystals in order to study the metal-insulator transition (MIT) ruling out an ambiguity due to inhomogeneous distribution of impurities. The critical exponent for the zero-temperature conductivity is 0.5 in zero magnetic field and 1.1 in magnetic fields. Variable-range-hopping conduction of the insulating samples and finite-temperature scaling analysis of the MIT induced by the external magnetic field are also discussed.