Mott transition

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

Superconductivity effect on electrical conduction in insulating granular films.

Abstract: We report the temperature and magnetic-field dependence of electrical resistance of indium/indium-oxide (In/InO x ) composite granular films in the insulating regime. The films show Mott variable-range hopping behavior at high temperatures, crossing over to a region of a much stronger temperature dependence of resistance near the superconducting transition temperature T c of the grains. Below the crossover temperature the films show a large and negative magnetoresistance with a field dependence of In[R(T,H)/R(T,O)] ∞ H 2 in the low-field limit

One-dimensional Bose-Hubbard model with local three-body interactions

Abstract: We employ the (dynamical) density-matrix renormalization-group technique to investigate the ground-state properties of the Bose-Hubbard model with nearest-neighbor transfer amplitudes $t$ and local two-body and three-body repulsion of strength $U$ and $W$, respectively. We determine the phase boundaries between the Mott-insulating and superfluid phases for the lowest two Mott lobes from the chemical potentials. We calculate the tips of the Mott lobes from the Tomonaga-Luttinger liquid parameter and confirm the positions of the Kosterlitz-Thouless points from the von Neumann entanglement entropy. We find that physical quantities in the second Mott lobe such as the gap and the dynamical structure factor scale almost perfectly in $t/(U+W)$, even close to the Mott transition. Strong-coupling perturbation theory shows that there is no true scaling but deviations from it are quantitatively small in the strong-coupling limit. This observation should remain true in higher dimensions and for not too large attractive three-body interactions.

Microscopic description of localization-delocalization transitions in BaFe 2 S 3

Abstract: We present a microscopic description of electronic reconstruction in BaFe2S3, a system which undergoes a pressure-induced insulator-metal transition followed by a superconducting phase at 24 K. We stress the importance of multiorbital electron-electron interactions for a consistent understanding of its intrinsic Mott-insulating and pressurized, orbital-selective metallic normal states. We explain the first-order nature of the Mott transition, showing that it is driven by dynamical spectral weight transfer in response to changes in the on-site Coulomb interaction to bandwidth ratio. As a by-product of this analysis, we unearth how dynamical correlations underpin spectroscopy and resistivity responses, in good agreement with experiment. Upon electron/hole doping, carrier localization is found to persist because the chemical potential lies in a gap structure with vanishing states near the Fermi energy. We detail the implications of our microscopic analysis for the underlying physics which emerges in the normal state of a compressed BaFe2S3 superconductor.

Fine-tuning the Mott metal–insulator transition and critical charge carrier dynamics in molecular conductors

Abstract: The unique possibilities of fine-tuning their physical properties in the vicinity of the Mott metal–insulator transition make the quasi-two-dimensional organic charge-transfer salts -(BEDT-TTF)X unprecedented model systems for studying the fundamentals of electron–electron correlations and the coupling between charge, spin and lattice degrees of freedom in reduced dimensions. The critical properties and the universality class of the Mott transition, however, are controversially debated for these materials, and information on the low-frequency dynamical properties of the correlated electrons is rather limited. By introducing fluctuation (noise) spectroscopy as a powerful new tool for studying the slow dynamics of charge carriers, in the past years we have been able to extract spectroscopic information on the coupling of charge carriers to the vibrational degrees of freedom of the crystal lattice. This is related to a glassy freezing of the BEDT-TTF molecules’ ethylene end-group (EEG) rotations at elevated ...

Orbital and spin correlations in Ca$_{2-x}$Sr$_x$RuO$_4$: A mean field study

Abstract: The alloy Ca$_{2-x}$Sr$_x$RuO$_4$ exhibits a complex phase diagram with peculiar magnetic metallic phases. In this paper some aspects of this alloy are discussed based on a mean field theory for an effective Kugel-Khomskii model of localized orbital and spin degrees of freedom. This model results from an orbital selective Mott transition which in the three-band system localized two orbitals while leaving the third one itinerant. Special attention is given to the region around a structure quantum phase transition at $ x \approx 0.5 $ where the crystal lattice changes from tetragonal to orthorhombic symmetry while leaving the system metallic. This transition yields, a change from ferromagnetic to antiferromagnetic spin correlations. The complete mean field phase diagram for this transition is given including orbital and spin order. The anisotropy of spin susceptibility, a consequence of spin-orbit coupling and orbital correlation, is a tell-tale sign of one of these phases. In the predominantly antiferromagnetic phase we describe a metamagnetic transition in a magnetic field and show that coupling of the itinerant band to the localized degrees of freedom yields an anomalous longitudinal magnetoresistance transition. Both phenomena are connected with the evolution of the ferromagnetic and antiferromagnetic domains in the external magnetic field and agree qualitatively with the experimental findings.