Disorder-Driven Metal-Insulator Transitions in Deformable Lattices.
We show that, in the presence of a deformable lattice potential, the nature of the disorder-driven metal-insulator transition is fundamentally changed with respect to the noninteracting (Anderson) scenario. For strong disorder, even a modest electron-phonon interaction is found to dramatically renormalize the random potential, opening a mobility gap at the Fermi energy. This process, which reflects disorder-enhanced polaron formation, is here given a microscopic basis by treating the lattice deformations and Anderson localization effects on the same footing. We identify an intermediate "bad insulator" transport regime which displays resistivity values exceeding the Mott-Ioffe-Regel limit and with a negative temperature coefficient, as often observed in strongly disordered metals. Our calculations reveal that this behavior originates from significant temperature-induced rearrangements of electronic states due to enhanced interaction effects close to the disorder-driven metal-insulator transition.
Institute of Physics and Astrophysics, University of Würzburg, Würzburg, Germany.|Consiglio Nazionale delle Ricerche (CNR-SPIN), Via Vetoio, L'Aquila, Italy.
Domenico
D
Di Sante
Institut Néel-CNRS and Université Grenoble Alpes, Boîte Postale 166, F-38042 Grenoble Cedex 9, France.
Simone
S
Fratini
Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA.
Vladimir
V
Dobrosavljević
Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, L'Aquila, Italy I-67100.|Consiglio Nazionale delle Ricerche (CNR-ISC) Via dei Taurini, Rome, Italy I-00185.
Sergio
S
Ciuchi