Mott transition

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

The highly nonperturbative nature of the Mott metal-insulator transition: Two-particle vertex divergences in the coexistence region

Abstract: We thoroughly analyze the divergences of the irreducible vertex functions occurring in the charge channel of the half-filled Hubbard model in close proximity to the Mott metal-insulator transition (MIT). In particular, by systematically performing dynamical mean-field theory (DMFT) calculations on the two-particle level, we determine the location and the number of the vertex divergences across the whole coexistence region adjacent to the first-order metal-to-insulator transition. We find that the lines in the parameter space, along which the vertex divergences occur, display a qualitatively different shape in the coexisting metallic and insulating phase, which is also associated to an abrupt jump of the number of divergences across the MIT. Physically, the systematically larger number of divergences on the insulating side of the transition reflects the sudden suppression of local charge fluctuation at the MIT. Further, a systematic analysis of the results demonstrates that the number of divergence lines increases as a function of the inverse temperature ${\beta\!=\!(k_\mathrm{B} T)^{-1}}$ by approaching the Mott transition in the zero temperature limit. This makes it possible to identify the zero-temperature MIT as an accumulation point of an infinite number of vertex divergence lines, unveiling the highly nonperturbative nature of the underlying transition.

Terminable Transitions in a Topological Fermionic Ladder

Abstract: Interacting fermionic ladders are important platforms to study quantum phases of matter, such as different types of Mott insulators. In particular, the D-Mott and S-Mott states hold pre-formed fermion pairs and become paired-fermion liquids upon doping (d-wave and s-wave, respectively). We show that the D-Mott and S-Mott phases are in fact two facets of the same topological phase and that the transition between them is terminable. These results provide a quantum analog of the well-known terminable liquid-to-gas transition. However, the phenomenology we uncover is even richer, as in contrast to the former, the order of the transition can be tuned by the interactions from continuous to first-order. The findings are based on numerical results using the variational uniform matrix-product state (VUMPS) formalism for infinite systems, and the density-matrix renormalization group (DMRG) algorithm for finite systems. This is complemented by analytical field-theoretical explanations. In particular, we present an effective theory to explain the change of transition order, which is potentially applicable to a broad range of other systems. The role of symmetries and edge states are briefly discussed.

Hubbard Bands, Mott Transition and Deconfinement in Strongly Correlated Systems

Abstract: The problem of deconfinement phases in strongly correlated systems is discussed. In space-time dimension $d=3+1$, a competition of confinement and Coulomb phases occurs, but in $d=2+1$ the confining phase dominates owing to monopole proliferation, but gapless fermion excitations can change the situation. Combining the Kotliar-Ruckenstein representation and fractionalized spin-liquid deconfinement picture, the Mott transition and Hubbard subbands are treated, general expressions in the case of an arbitrary bare band spectrum being obtained. The transition into a metallic state is determined by condensation of a gapless boson mode. The spectrum picture in the insulating state is considerably influenced by the spinon spin-liquid spectrum and hidden Fermi surface.

Phase transitions in nonequilibrium electron-hole systems of Si/SiGe/Si nanoheterostructures

Abstract: The exciton condensation in a Si1−xGex solid solution layer of Si/Si1−xGex/Si heterostructures with the formation of electron-hole liquid has been investigated by low-temperature photoluminescence spectroscopy. In the temperature range above the critical temperature of the transition from an exciton gas to electron-hole liquid, a Mott transition from an exciton gas to electron-hole plasma has been found and investigated.

Temperature Dependences of Conductivity at Small Electron Mean Free Path

Abstract: It is demonstrated by consideration of available experimental data that the unusual temperature dependence of the conductivity σ(T) = σ0 + A exp [–B/T1/(1 + d)], d being the dimension, is typical for different disordered systems with a small electron mean free path. A possible explanation of this dependence is proposed in the framework of a model with two kinds of weakly hybridized electron states, taking into account phonon-induced transitions between them. It is assumed that such dependence σ(T) is a characteristic one for systems near the Mott transition. Es wird anhand verfugbarer experimenteller Daten gezeigt, das die ungewohnliche Temperatur-abhangigkeit der Leitfahigkeit σ(T) = σ0 + A exp [–B/T1/(1 + d)], wobei d die Dimension ist, typisch fur verschiedene fehlgeordnete Systeme mit einer geringen mittleren freien Weglange der Elektronen ist. Eine mogliche Erklarung dieser Abhangigkeit wird im Rahmen eines Modells mit zwei Arten schwach hybridisierter Elektronenzustande vorgeschlagen, wobei phononeninduzierte Ubergange zwischen beiden berucksichtigt werden. Es wird angenommen, das diese Abhangigkeit σ(T) charakteristisch fur Systeme in der Nahe des Mottubergangs ist.