Anderson localization effects near the Mott metal-insulator transition

Abstract

The interplay between Mott and Anderson routes to localization in disordered interacting systems gives rise to different transitions and transport regimes. Here, we investigate the phase diagram at finite temperatures using dynamical mean field theory combined with typical medium theory, which is an effective theory of the Mott-Anderson metal-insulator transition. We mainly focus on the properties of the coexistence region associated with the Mott phase transition. For weak disorder, the coexistence region is found to be similar as in the clean case. However, as we increase disorder Anderson localization effects are responsible for shrinking the coexistence region and at sufficiently strong disorder (approximately equal to twice the bare bandwidth) it drastically narrows, the critical temperature abruptly goes to zero, and we observe a phase transition in the absence of a coexistence of the metallic and insulating phases. In this regime, the effects of interaction and disorder are found to be of comparable importance for charge localization.Comment: minor changes, 8 pages, 9 figure

Effects of Disorder on the Pressure-Induced Mott Transition in κ-(BEDT-TTF)2Cu[N(CN)2]Cl

“…Thus, we conclude that exposure to X-ray for 50 h and 100 h induces a degree of disorder which is small enough to conserve essential Mott properties. This interpretation is supported by theoretical results [37,41,59] which indicate a sharp metal-insulator transition, accompanied by a sizable coexistence regime, at a critical interaction strength U c at T = 0, similar to the clean Mott system. However, even though retaining its first-order character, we find that the transition becomes distinctly weaker upon irradiation, as evidenced by a significant shrinkage of the discontinuities in the length change and resistance in the 50 h and 100 h irradiated samples, as compared to the pristine ones.…”

“…These observations are in line with theoretical predictions: The calculations reveal a sizable reduction of the size of the coexistence region upon an initial increase in disorder [37], reflecting the weakening of the first-order transition. In addition, recent finite-temperature calculations suggest a sudden drop of T c to zero [41] and a continuous change from a metal to an insulator above some critical value of the degree of disorder. The present data do not allow to conclude that the character of the transition changes from first to second order.…”

Mott Quantum Criticality in the Anisotropic 2D Hubbard Model

“…Moreover, various numerical studies find that T c remains finite also in the presence of lattice frustration [24][25][26][27][28][29][30]. Finally, while the effective suppression of T c can be achieved with disorder, it requires the proper treatment of Anderson localization effects [31][32][33].…”

Ab initiotypical medium theory of substitutional disorder

“…The typical value of the LDOS is well represented by the geometric average 32 ρ typ (E) = exp[ ln ρ i (E) ], where ... represents the arithmetic average over disorder and ρ i (E) is the LDOS at site i for the energy E 33 . This technique was successfully applied to model Hamiltonians and is referred to as "typical medium theory" (TMT) [34][35][36][37][38][39][40] . The TMT can describe signatures of Anderson localization in the spectral function, i.e., on the one-particle level, but does not capture short-range order effects.…”