Mechanism of hopping transport in disordered Mott insulators

Abstract

By using a combination of detailed experimental studies and simple theoretical arguments, we identify a novel mechanism characterizing the hopping transport in the Mott insulating phase of Ca${}_{2-x}$Sr${}_x$RuO${}_4$ near the metal-insulator transition. The hopping exponent $\alpha$ shows a systematic evolution from a value of $\alpha =1/2$ deeper in the insulator to the conventional Mott value $\alpha =1/3$ closer to the transition. This behavior, which we argue to be a universal feature of disordered Mott systems close to the metal-insulator transition, is shown to reflect the gradual emergence of disorder-induced localized electronic states populating the Mott-Hubbard gap.

arXiv comment5 pages, 3 figures, To be published in Physical Review Letters

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• Current-Induced Gap Suppression in the Mott Insulator Ca${}_2$RuO${}_4$
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• Dynamical Mean Field Study of the Two-Dimensional Disordered Hubbard Model
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• Self-generated electronic heterogeneity and quantum glassiness in the high temperature superconductors
• Evidence for Charge Glass-like Behavior in Lightly Doped La_{2-x}Sr_{x}CuO_{4} at Low Temperatures
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• Orbital-selective Mass Enhancements in Multi-band Ca${}_{2-x}$Sr${}_x$RuO${}_4$ Systems Analyzed by the Extended Drude Model
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• Magnon dispersion in Ca2RuO4: impact of spin-orbit coupling and oxygen moments
• Orbitally selective breakdown of Fermi liquid quasiparticles in Ca${}_{1.8}$Sr${}_{0.2}$RuO${}_4$
• Anisotropic uniaxial pressure response of the Mott insulator Ca2RuO4
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• Magic thickness of 25 Å makes periodic metal-insulator transitions