Topic
Mott transition
About: Mott transition is a research topic. Over the lifetime, 2444 publications have been published within this topic receiving 78401 citations.
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01 Dec 2006
TL;DR: In this paper, the authors investigated the relation between the strength of the electron correlation and the low-temperature thermoelectric performance using layered compound 1T•TaS2 as a test material.
Abstract: Using layered compound 1T‐TaS2 as a test material, this study investigated the relation between the strength of the electron correlation and the low‐temperature thermoelectric performance. The thermoelectric figure of merit S2(ρκ)−1 and power factor S2/ρ in the Mott insulator phase increase with increasing Mott transition temperature (Tc) because of the enhancement of thermoelectric power in the mid‐gap state of 1T‐TaS2. This is experimental evidence that the electron correlation (Coulomb repulsion) enhances thermoelectric performance in strongly correlated electron materials.
3 citations
TL;DR: Using an extension of the Gutzwiller approximation for an inhomogeneous system, the two-band Hubbard model with unequal band widths for a slab geometry is studied to investigate the mutual effect of individual bands on the spatial distribution of quasi-particle weight and charge density, especially near the surface of the slab.
Abstract: Using an extension of the Gutzwiller approximation for an inhomogeneous system, we study the two-band Hubbard model with unequal band widths for a slab geometry. The aim is to investigate the mutual effect of individual bands on the spatial distribution of quasi-particle weight and charge density, especially near the surface of the slab. The main effect of the difference in band width is the presence of two different length scales corresponding to the quasi-particle profile of each band. This is enhanced in the vicinity of the critical interaction of the narrow band where an orbitally selective Mott transition occurs and a surface dead layer forms for the narrow band. For the doped case, two different regimes of charge transfer between the surface and the bulk of the slab are revealed. The charge transfer from surface/center to center/surface depends on both the doping level and the average relative charge accumulated in each band. Such effects could also be of importance when describing the accumulation of charges at the interface between structures made of multi-band strongly correlated materials.
3 citations
TL;DR: In this paper, the effects of Si doping well beyond the Mott transition limit on structural, electrical, and optical properties of PAMBE-grown GaN layers were studied, showing that Si doping up to a doping density of 1.0×1020 cm-3 resulted in rough surface morphology and degraded crystal quality.
Abstract: The effects of Si doping well beyond the Mott transition limit on structural, electrical, and optical properties of plasma assisted molecular beam epitaxy (PAMBE) grown GaN layers were studied. Si doping up to a doping density of 1.0×1020 cm-3 resulted in rough surface morphology and degraded crystal quality. It also showed higher tensile strain, but did not result in cracking. Irrespective of the surface morphology and structural quality, the sheet resistance systematically decreased with increased carrier concentration up to and beyond the doping density of 1.0×1020 cm-3. PL study revealed three distinctive characteristics with Si doping: first, yellow luminescence is absent in Si doped samples‒ an indication of occupied VGa-ON and CN states in the bandgap; second, a distinctive luminescence peak is observed next to the band edge luminescence for the samples doped beyond 2.1×1019 cm-3 ‒ probably an indication of localization of some of the electrons either at donors or at excitons bound to defects; third, blue shift of the band edge luminescence is not matching with the calculated Moss-Burstein shift for doping densities beyond 2.1×1019cm-3‒an indication of some of the electrons not occupying higher levels of conduction band, which is consistent with the 2nd observation of localization of electrons near the donors or excitons bound to surface defects.
3 citations
TL;DR: In this article , the authors theoretically study the phase transitions of FePS$_3$ using first-principles methods based on density functional theory and embedded dynamical mean field theory.
Abstract: The layered metal phosphorous trisulfide FePS$_3$ is reported to be a Mott insulator at ambient conditions and to undergo structural and insulator-metal phase transitions under pressure. However, the character of the resulting metallic states has not been understood clearly so far. Here, we theoretically study the phase transitions of FePS$_3$ using first-principles methods based on density functional theory and embedded dynamical mean field theory. We find that the Mott transition in FePS$_3$ can be orbital-selective, with $t_{2g}$ states undergoing a correlation-induced insulator-to-metal transition while $e_g$ states remain gapped. We show that this orbital-selective Mott phase, which occurs only when non-hydrostatic pressure is used, is a bad metal (or non-Fermi liquid) with large fluctuating moments due to Hund's coupling. Further application of pressure increases the crystal-field splitting and converts the system to a conventional Fermi liquid with low-spin configurations dominant. Our results show that FePS$_3$ is a novel example of a system that realizes an orbital-selective Mott phase, allowing tuning between correlated and uncorrelated metallic properties in an accessible pressure range ($\leq$ 18 GPa).
3 citations
3 citations