Mott transition

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

Magnetic field-induced metal-insulator transition in InP: new result at very low temperatures

Abstract: The metal-insulator transition in compensated n-type indium phosphide, with an impurity concentration just above the critical concentration obtained from the Mott criterion has been induced by a magnetic field. First-order phenomena are considered, corrections to the conductivity due to electron-electron interaction or quantum interferences in the metallic regime will be described elsewhere. Two aspects of the MI transition (Anderson and Mott transitions) are observed by increasing the magnetic field at temperatures down to 50 mK. The Mott minimum metallic conductivity, whose existence has been shown earlier at higher temperatures, is still found down to the lowest attainable temperatures, and its value remains in agreement with the first Mott estimation. For a sample near the MI transition, arguments are given for conduction mechanisms occurring in the impurity band rather than in a tail of the conduction band.

Mott transition in the π -flux S U ( 4 ) Hubbard model on a square lattice

Abstract: With increasing repulsive interaction, we show that a Mott transition occurs from the semimetal to the valence bond solid, accompanied by the ${Z}_{4}$ discrete symmetry breaking. Our simulations demonstrate the existence of a second-order phase transition, which confirms the Ginzburg-Landau analysis. The phase transition point and the critical exponent $\ensuremath{\eta}$ are also estimated. To account for the effect of a $\ensuremath{\pi}$ flux on the ordering in the strong-coupling regime, we analytically derive by the perturbation theory the ring-exchange term, which is the leading-order term that can reflect the difference between the $\ensuremath{\pi}$-flux and zero-flux $SU(4)$ Hubbard models.

Direct observation of the M2 phase with its Mott transition in a VO$_2$ film

Abstract: In VO$_2$, the explicit origin of the insulator-to-metal transition is still disputable between Peierls and Mott insulators. Along with the controversy, its second monoclinic (M2) phase has received considerable attention due to the presence of electron correlation in undimerized vanadium ions. However, the origin of the M2 phase is still obscure. Here, we study a granular VO$_2$ film using conductive atomic force microscopy and Raman scattering. Upon the structural transition from monoclinic to rutile, we observe directly an intermediate state showing the coexistence of monoclinic M1 and M2 phases. The conductivity near the grain boundary in this regime is six times larger than that of the grain core, producing a donut-like landscape. Our results reveal an intra-grain percolation process, indicating that VO$_2$ with the M2 phase is a Mott insulator.

Exciton Mott transition revisited

Abstract: The dissociation of excitons into a liquid of holes and electrons in photoexcited semiconductors, despite being one of the first recognized examples of a Mott transition, still defies a complete understanding, especially regarding the nature of the transition, which is found to be continuous in some cases and discontinuous in others. Here we consider an idealized model of photoexcited semiconductors that can be mapped onto a spin-polarized half-filled Hubbard model, whose phase diagram reproduces most of the phenomenology of those systems and uncovers the key role of the exciton binding energy in determining the nature of the exciton Mott transition. We find indeed that the transition changes from discontinuous to continuous as the binding energy increases. Moreover, we uncover a rather anomalous electron-hole liquid phase next to the transition, which still sustains excitonic excitations despite being a degenerate Fermi liquid of heavy mass quasiparticles.