Quantum Spin Liquids and the Metal-Insulator Transition in Doped Semiconductors

• Main Authors: Potter, Andrew Cole (Contributor), Barkeshli, Maissam (Author), McGreevy, John (Contributor), Todadri, Senthil (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2012-10-11T15:07:13Z.
• Subjects: Article
• Online Access: Get fulltext

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.
Alfred P. Sloan Foundation (Cooperative Research Agreement DE-FG0205ER41360)
United States. Dept. of Energy (Cooperative Research Agreement DE-FG0205ER41360)
National Science Foundation (U.S.) (Grant DMR-1005434)