Alejandro Cabo-Bizet

Spontaneous symmetry breaking approach to La2CuO4 properties: Hints for matching the Mott and Slater pictures

Abstract Special solutions of the Hartree–Fock (HF) problem for Coulomb interacting electrons described by a simple model of the Cu–O planes in La 2 CuO 4 are presented. One of the mean field states obtained, is able to predict some of the most interesting properties of this material, such as its insulator character and the antiferromagnetic order. The natural appearance of pseudogaps in some states of this material is also indicated by another of the HF states obtained. These surprising results follow after eliminating spin and crystal symmetry restrictions usually imposed on the single particle HF orbitals, by employing the rotational invariant formulation of the HF scheme originally introduced by Dirac. Therefore, it is exemplified here, how up to know considered strong correlation effects, can be described by improving the HF solution of the considered system. In other words, it has been argued, that defining correlation effects as the ones shown by the system and not predicted by the HF best (lowest energy) solution, allows to explain important, up to know considered as strong correlation properties, as simple mean field ones. The discussion also helps to clarify the role of the antiferromagnetism and pseudogaps in the physical properties of the HTSC materials and indicates a promising way to start conciliating the Mott and Slater pictures in the physics of the transition metal oxides and other strongly correlated electron systems.

Hartee Fock Symmetry Breaking Effects in La 2 CuO 4 : Hints for connecting the Mott and Slater Pictures and Pseudogap Prediction

Abstract: This work expands the results and derivations presented in a recent letter. It isargued that symmetry breaking Hartree-Fock (HF) solutions of a simple model of the Cu-Oplanes in La 2 CuO 4 , are able to describe the insulator and antiferromagnetic characters ofthis material. Then, this classical primer of a Mott insulator is alternatively obtained hereas an exact Slater insulator within the simplest of the firstprinciples schemes. Moreover,pseudogap HF states are also predicted. The maximal energy gap of 100 meV over theFermi surface of this wavefunction, reasonably well matches the ARPES upper pseudogapmeasurements for La 2 CuO 4 in the zero doping limit. These surprising results followed aftereliminating spin and crystal symmetry constraints usually imposed on the HF orbitals. Thediscussion helps to clarify the role of the antiferromagnetism and pseudogaps in the physicsoftheHTSCmaterialsandindicatesapromisingwaytostartconciliatingtheMottandSlaterpictures for the description of the transition metal oxides.Keywords: symmetry breaking; strongly correlated electron systems; Magnetism; HTc su-percondutivity; HTSC; pseudgaps; MIS; entanglementClassification: PACS 71.10.Fd,71.15.Mb,71.27.+a,71.30.+h,74.20.-z,74.25.Ha,74.25.Jb,74.72.-h

HARTREE–FOCK SOLUTIONS OF 2D INTERACTING TIGHT-BINDING ELECTRONS: MOTT PROPERTIES AND ROOM TEMPERATURE SUPERCONDUCTIVITY INDICATIONS

Former results for a tight-binding (TB) model of CuO planes in La2CuO4 are reinterpreted here to underline their wider implications. It is noted that physical systems being appropriately described by the TB model can exhibit the main strongly correlated electron system (SCES) properties, when they are solved in the HF approximation, by also allowing crystal symmetry breaking effects and noncollinear spin orientations of the HF orbitals. It is argued how a simple 2D square lattice system of Coulomb interacting electrons can exhibit insulator gaps and pseudogap states, and quantum phase transitions as illustrated by the mentioned former works. A discussion is also presented here indicating the possibility of attaining room temperature superconductivity, by means of a surface coating with water molecules of cleaved planes of graphite, being orthogonal to its c-axis. The possibility that 2D arrays of quantum dots can give rise to the same effect is also proposed to consideration. The analysis also furnishes t...

Particle dynamics in a relativistic invariant stochastic medium

The dynamics of particles moving in a medium defined by its relativistically invariant stochastic properties is investigated. For this aim, the force exerted on the particles by the medium is defined by a stationary random variable as a function of the proper time of the particles. The equations of motion for a single one-dimensional particle are obtained and numerically solved. A conservation law for the drift momentum of the particle during its random motion is shown. Moreover, the conservation of the mean value of the total linear momentum for two particles repelling each other according to the Coulomb interaction also follows. Therefore, the results indicate the realization of a kind of stochastic Noether theorem in the system under study.