Mott transition

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

Anisotropic renormalization of quasiparticles in cuprate-oxide superconductors

Abstract: The Hubbard model on the simple square lattice in the vicinity of the Mott transition is considered by the 1/ d expansion method, with d being the spatial dimensionality. The superexchange interaction is enhanced by antiferromagnetic spin fluctuations, and its enhanced portion is similar to an interaction due to the so-called spin-fluctuation mechanism. Gutzwiller's heavy electrons are renormalized to be light by the enhanced superexchange interaction, which is responsible for high-temperature superconductivity; the formation of light quasiparticles occurs, in particular, for k s in the vicinity of saddle points in two dimensions. This anisotropic renormalization of quasi-particles can explain not only the anisotropic pseudogap in normal states but also other anomalous normal-state properties such as the large anisotropy of resistivity between the parallel and the perpendicular directions to CuO 2 planes.

Anistropic phenomena in strongly correlated electron systems

Abstract: This thesis is concerned with momentum anisotropy in strongly correlated electron systems, and explores its origin and its consequences through two contrasting projects. The first is a study of the temperature dependences of magnetotransport quantities in the normal state of the cuprate high-temperature superconductors. A phenomenological anisotropic small-angle scattering model is investigated; Hall effect measurements can be reproduced for parameters sufficiently close to particle-hole symmetry, but the experimentally observed magnetoresistance cannot be explained. The second project studies the phase diagram and quasiparticle properties of the square lattice Hubbard model within two-site cluster dynamical mean field theory (DMFT), at zero temperature. The "two-site" approach provides a drastically simplified but physically motivated self-consistency scheme for DMFT. This is combined for the first time with cluster DMFT, within which different magnetic orders and momentum anisotropy may be represented consistently. The extent of antiferromagnetism is determined; phases are discovered where the Fermi surface consists of small hole pockets, and the Mott transition happens as these pockets shrink to points. Anisotropic phenomena observed in the cuprates are reproduced by the theory; a pseudogap destroys the Fermi surface in some places, leaving behind Fermi arcs that closed into hole pockets by lines with very small quasiparticle residue.

Lattice response at the Mott Transition in a Quasi-2D Organic Conductor

Abstract: Discontinuous changes of the lattice parameters at the Mott metal-insulator transition are detected by high-resolution dilatometry on deuterated crystals of the layered organic conductor kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br. The uniaxial expansivities uncover a striking and unexpected anisotropy, notably a zero effect along the in-plane c axis along which the electronic interactions are relatively strong. A huge thermal expansion anomaly is observed near the end point of the first-order transition line enabling us to explore the critical behavior with very high sensitivity. The analysis yields critical fluctuations with an exponent alpha approximately 0.8+/-0.15 at odds with the novel criticality recently proposed for these materials [Kagawa et al., Nature (London) 436, 534 (2005)]. Our data suggest an intricate role of the lattice degrees of freedom in the Mott transition for the present materials.