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Mardi 14 mai 2019 - 14:00

Quantum critical transport at the metal-insulator transition

Prosenjit Haldar (LPT Toulouse)

par Revaz Ramazashvili - 14 mai 2019

In contrast to the first-order correlation-driven Mott metal-insulator transition (MIT), continuous disorder-driven transitions are intrinsically quantum critical. Here, we investigate transport quantum criticality in the Falicov-Kimball model, a representative of the latter class in the "strong disorder" category. Employing cluster-dynamical mean-field theory (CDMFT), we find clear and anomalous quantum critical scaling behavior manifesting as perfect mirror symmetry of scaling curves on both sides of the MIT. Surprisingly, we find that the beta-function scales like log(g) deep into the bad-metallic phase as well, providing sound unified basis for these findings. We argue that such "strong localization" quantum criticality may manifest in real three-dimensional systems where disorder effects are more important than electron-electron interactions. We find that these surprising results are in comprehensive and very good accord with signatures of a novel kind of localization in disordered NbTiN near the MIT, providing substantial support for our "strong" localization view.

Post-scriptum :

contact : G. Lemarié, B. Georgeot