Zusammenfassung
Recent studies of electrical transport, both theoretical and experimental,
near the bandwidth-tuned Mott metal-insulator transition have uncovered
apparent quantum critical scaling of the electrical resistivity at elevated
temperatures, despite the fact that the actual low-temperature phase transition
is of first order. This raises the question whether there is a hidden Mott
quantum critical point. Here we show that the dynamical mean-field theory of
the Hubbard model admits, in the low-temperature limit, asymptotically
scale-invariant (i.e. power-law) solutions, corresponding to the metastable
insulator at the boundary of metal-insulator coexistence region, which can be
linked to the physics of the pseudogap Anderson model. While our
state-of-the-art numerical renormalization group calculations reveal that this
asymptotic regime is restricted to very small energies and temperatures, we
uncover the existence of a wide crossover regime where the single-particle
spectrum displays a different power law. We show that it is this
power-law regime, corresponding to approximate local quantum criticality, which
is continuously connected to and hence responsible for the apparent quantum
critical scaling above the classical critical end point. We connect our
findings to experiments on tunable Mott materials.
Nutzer