Mott transition

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

Near-adiabatic parameter changes in correlated systems: influence of the ramp protocol on the excitation energy

Abstract: In this work, we study the excitation energy for slow changes of the hopping parameter in the Falicov–Kimball model with nonequilibrium dynamical mean-field theory. The excitation energy vanishes algebraically for long ramp times with an exponent that depends on whether the ramp takes place within the metallic phase, within the insulating phase or across the Mott transition line. For ramps within the metallic or the insulating phase, the exponents are in agreement with a perturbative analysis for small ramps. The perturbative expression quite generally shows that the exponent depends explicitly on the spectrum of the system in the initial state and on the smoothness of the ramp protocol. This explains the qualitatively different behaviors of gapless (e.g. metallic) and gapped (e.g. Mott insulating) systems. For gapped systems the asymptotic behavior of the excitation energy depends only on the ramp protocol and its decay becomes faster for smoother ramps. For gapless systems and sufficiently smooth ramps the asymptotics are ramp independent and depend only on the intrinsic spectrum of the system. However, the intrinsic behavior is unobservable if the ramp is not smooth enough. This is relevant for ramps to small interaction in the fermionic Hubbard model, where the intrinsic cubic fall-off of the excitation energy cannot be observed for a linear ramp due to its kinks at the beginning and the end.

Influence of disorder on incoherent transport near the Mott transition

Abstract: We calculate the optical and dc conductivity for half-filled disordered Hubbard model near the Mott metal-insulator transition. As in the clean case, large metallic resistivity is driven by a strong inelastic scattering, and Drude-like peak in the optical conductivity persists even at temperatures when the resistivity is well beyond the semiclassical Mott-Ioffe-Regel limit. Local random potential does not introduce new charge carriers but it induces effective local carrier doping and broadens the bandwidth. This makes the system more metallic, in agreement with the recent experiments on x-ray irradiated charge-transfer salts.

Condensed-matter physics with light and atoms: Strongly correlated cold fermions in optical lattices

Abstract: Various topics at the interface between condensed matter physics and the physics of ultra-cold fermionic atoms in optical lattices are discussed The lectures start with basic considerations on energy scales, and on the regimes in which a description by an effective Hubbard model is valid Qualitative ideas about the Mott transition are then presented, both for bosons and fermions, as well as mean-field theories of this phenomenon Antiferromagnetism of the fermionic Hubbard model at half-filling is briefly reviewed The possibility that interaction effects facilitate adiabatic cooling is discussed, and the importance of using entropy as a thermometer is emphasized Geometrical frustration of the lattice, by suppressing spin long-range order, helps revealing genuine Mott physics and exploring unconventional quantum magnetism The importance of measurement techniques to probe quasiparticle excitations in cold fermionic systems is emphasized, and a recent proposal based on stimulated Raman scattering briefly reviewed The unconventional nature of these excitations in cuprate superconductors is emphasized

Unconventional Mott transition in K x Fe 2 − y Se 2

Abstract: The newly discovered 122-iron-chalcogenide superconductors show clear signatures of Mott-insulating and strange, incoherent metal normal states. Motivated thereby, we use local-density approximation plus dynamical mean-field theory (LDA + DMFT) to study the electronic structure and transport properties of K${}_{x}$Fe${}_{2\ensuremath{-}y}$Se${}_{2}$. We find that the undoped KFe${}_{1.6}$Se${}_{2}$ system is a new kind of Mott-Kondo insulator (MKI). Electron doping this MKI drives a Mott transition to an orbital-selective non-Fermi-liquid metal. Good agreement with spectral and transport responses supports our view, implying that superconductivity arises from a doped Mott insulator, as in the high-${T}_{c}$ cuprates.

Emergence of a common energy scale close to the orbital-selective Mott transition.

Abstract: We calculate the spectra and spin susceptibilities of a Hubbard model with two bands having different bandwidths but the same on-site interaction, with parameters close to the orbital-selective Mott transition, using dynamical mean-field theory. If the Hund's rule coupling is sufficiently strong, one common energy scale emerges which characterizes both the location of kinks in the self-energy and extrema of the diagonal spin susceptibilities. A physical explanation of this energy scale is derived from a Kondo-type model. We infer that for multiband systems local spin dynamics rather than spectral functions determine the location of kinks in the effective band structure.