Mott transition

About: Mott transition is a research topic. Over the lifetime, 2444 publications have been published within this topic receiving 78401 citations.

Phase Diagram of Cuprate High-Temperature Superconductors Described by a Field Theory Based on Anharmonic Oxygen Degrees of Freedom

Abstract: In high temperature superconductors, although some phenomena such as the Mott transition (MT) at low doping are clearly driven by electron correlations, recent experimental data imply that anharmonic oxygen degrees of freedom---characteristic of perovskite materials---are playing a significant role. A key test of the role of anharmonic oxygen is to reproduce the complex cuprate phase diagram from a simple model. Here, we show that a field theory based on nonlinear coupling to anharmonic oxygens, parametrized from ab initio calculations, quantitatively reproduces the cuprate phase diagram for dopings above the MT. Pairing is mediated by renormalized oxygen vibrations transmuted into excitations of the pseudogap. The observed strong dependence of gap to transition temperature ratio on ${T}_{c}$ also emerges from this field theory. This work suggests that including vibrational degrees of freedom is key to developing a complete understanding of the cuprates.

Electron transport near the Mott transition in n-GaAs and n-GaN

Abstract: In this paper, we study the temperature dependence of the conductivity and the Hall coefficient near the metal–insulator phase transition. A theoretical investigation is performed within the effective mass approximation. The variational method is used to calculate the eigenvalues and eigenfunctions of the impurity states. Unlike previous studies, we have included nonlinear corrections to the screened impurity potential, because the Thomas–Fermi approximation is incorrect for the insulator phase. It is also shown that near the phase transition the exchange interaction is essential. The obtained temperature dependencies explain several experimental measurements in gallium arsenide (GaAs) and gallium nitride (GaN).

Nanoscale self-organization and metastable non-thermal metallicity in Mott insulators

Abstract: Mott transitions in real materials are first order and almost always associated with lattice distortions, both features promoting the emergence of nanotextured phases. This nanoscale self-organization creates spatially inhomogeneous regions, which can host and protect transient non-thermal electronic and lattice states triggered by light excitation. Here, we combine time-resolved X-ray microscopy with a Landau-Ginzburg functional approach for calculating the strain and electronic real-space configurations. We investigate V2O3, the archetypal Mott insulator in which nanoscale self-organization already exists in the low-temperature monoclinic phase and strongly affects the transition towards the high-temperature corundum metallic phase. Our joint experimental-theoretical approach uncovers a remarkable out-of-equilibrium phenomenon: the photo-induced stabilisation of the long sought monoclinic metal phase, which is absent at equilibrium and in homogeneous materials, but emerges as a metastable state solely when light excitation is combined with the underlying nanotexture of the monoclinic lattice.

Light emission lifetimes in p-type δ-doped GaAs/AlAs multiple quantum wells near the Mott transition

Abstract: The time resolved photoluminescence of beryllium δ-doped GaAs/AlAs multiple quantum wells have been studied over a range of doping concentrations, in order to investigate possible mechanisms for the carrier radiative recombination, both above and below the Mott metal-insulator transition. It was found that at doping concentrations near the Mott transition (NBe ∼ 3 × 1012 cm−2), the radiative recombination of excitons-bound-to-acceptor impurities as well as free electrons with acceptor impurities, dominated in the Be δ-doped GaAs/AlAs MQWs (LW = 15 nm) that were used in this study. Above the Mott transition, the major contribution was from radiative recombination of free electrons with a two-dimensional hole gas. The radiative lifetime would therefore exhibit different behavior with doping. In lightly doped GaAs/AlAs MQWs, this changed from 0.3–1 ns at 3.6 K to 8 ns at 300 K, whilst in quantum wells above the Mott transition, it changed from ∼0.36 ns at 3.6 K to ∼1 ns at 300 K, and was also weakly dependen...