Phys Rev Lett. 2012 Aug 17;109(7):077205. doi: 10.1103/PhysRevLett.109.077205. Epub 2012 Aug 16.

Quantum spin liquids and the metal-insulator transition in doped semiconductors.

Physical review letters

Andrew C Potter, Maissam Barkeshli, John McGreevy, T Senthil

PMID: 23006401 DOI: 10.1103/PhysRevLett.109.077205

Abstract

We describe a new possible route to the metal-insulator transition in doped semiconductors such as Si:P or Si:B. We explore the possibility that the loss of metallic transport occurs through Mott localization of electrons into a quantum spin liquid state with diffusive charge neutral "spinon" excitations. Such a quantum spin liquid state can appear as an intermediate phase between the metal and the Anderson-Mott insulator. An immediate testable consequence is the presence of metallic thermal conductivity at low temperature in the electrical insulator near the metal-insulator transition. Further, we show that though the transition is second order, the zero temperature residual electrical conductivity will jump as the transition is approached from the metallic side. However, the electrical conductivity will have a nonmonotonic temperature dependence that may complicate the extrapolation to zero temperature. Signatures in other experiments and some comparisons with existing data are made.

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• Journal Article