Colloquia

According to early ideas of Mott and Anderson, the interaction-­driven metal-­insulator transition “the Mott transition“ remains a sharp T=0 phase transition even in absence of any spin or charge ordering.  Should this phase transition be regarded as a quantum critical point?  To address this question, here we examine the phase diagram and transport properties of the maximally frustrated half-­filled Hubbard model, in the framework of dynamical mean-­field theory (DMFT).  We identify a quantum Widom line (QWL) which defines the center of the corresponding quantum critical region associated with Mott metale insulator transition for this model.  The evolution of resistivity with temperature is then evaluated along trajectories following (parallel to) the QWL, displaying remarkable scaling behavior characteristic of quantum criticality.  Precisely this kind of behavior was found in very recent experiments on organic Mott systems [1,2].  In the case of the doping-driven Mott transition, we show that the mysterious Bad Metal behavior (T-linear resistivity around the Mott-Ioffee- Regel limit) coincides with the Quantum Critical region of the Mott transition.

[1] Quantum criticality of Mott transition in organic materials, Tetsuya Furukawa, Kazuya Miyagawa, Hiromi Taniguchi, Reizo Kato & Kazushi Kanoda, Nature Physics, 9 Feb.  2015; doi:10.1038/nphys3235.

[2] See also:

http://condensedconcepts.blogspot.com/2015/03/quantum-criticality-near-mott.html