One-particle spectral function and local density of states in a phenomenological mixed-phase model for high-temperature superconductors

Abstract

The dynamical properties of a recently introduced phenomenological model for high temperature superconductors are investigated. In the clean limit, it was observed that none of the homogeneous or striped states that are induced by the model at low temperatures can reproduce the recent angleresolved photoemission results for LSCO (Yoshida et al., Phys. Rev. Lett., 91, 027001 (2003)), that show a signal with two branches in the underdoped regime. On the other hand, upon including quenched disorder in the model and breaking the homogeneous state into "patches" that are locally either superconducting or antiferromagnetic, the two-branch spectra can be reproduced. In this picture, the nodal regions are caused by d-wave superconducting clusters. Studying the density of states (DOS), a pseudogap is observed, caused by the mixture of the gapped antiferromagnetic state and a d-wave superconductor. The local DOS can be interpreted using a mixed-phase picture, similarly as observed in tunneling experiments. It is concluded that a simple phenomenological model for cuprates can capture many of the features observed in the underdoped regime of these materials.

Strong charge fluctuations manifested in the high-temperature Hall coefficient of high-Tccuprates

“…1, in those samples the behavior of R H (T ) at high temperature is surprisingly similar to that observed in lightly-doped samples and is changing only gradually with doping; this observation strongly suggests that essentially the same thermal activation process is affecting the R H (T ) behavior at high temperature even in the superconducting doping range. 35 Motivated by this qualitative observation, we attempt to understand the high-temperature R H (T ) behavior for x ≥ 0.08 in terms of a crude phenomenological two-carrier model, remembering that the occurrence of an electronic heterogeneity (microscopic phase separation or coexistence of different types of carriers) has been discussed repeatedly for LSCO; 6,36,37,38,39,40,41 for example, doping evolutions of the magnetic susceptibility 36 or the superfluid density 37 have been discussed to reflect an electronic heterogeneity. In the following analysis, we crudely hypothesize that there are two types of holes, those that live on the Fermi arc (or small hole pockets), and others that live on a large Fermi surface (FS).…”

Testing the Monte Carlo–mean field approximation in the one-band Hubbard model

“…[31][32][33][34][35] A similar approach has been used in the context of the Bogoliubov de Gennes (BdG) equations, allowing for the study of regimes beyond weak coupling BCS. [36][37][38][39] It should be stressed that none of the spin-fermion models, either in the manganite or cuprate context, exhibit a sign problem. Thus, computational studies are possible at any electronic density, temperature, and range of electronic hopping.…”

“…To our knowledge, the first time that this methodology was proposed was in a study of the competition between AFM and superconducting (SC) tendencies in the one-orbital Hubbard model. 38 In this earlier work, both the staggered AFM field and a complex field representing the SC order parameter deduced from the BdG equations were introduced and handled via Monte Carlo simulations. Similar studies involving competing AFM and SC states within the Heisenberg model were presented in Refs.…”

Parallelized traveling cluster approximation to study numerically spin-fermion models on large lattices

“…Earlier similar approaches but for the attractive Hubbard interaction (negative U ) where reported in Refs. [34][35][36][37][57][58][59].…”

“…Some well known methods in this context include the study of electron-phonon systems [14,15], the Born-Oppenheimer approximation [16], and the Car-Parrinello method [17]. Spin-fermion models for the manganites [13,[18][19][20][21][22][23][24], double perovskites [25,26], nickelates [27,28], copper based high temperature superconductors [29][30][31][32][33], BCS superconductors [34][35][36][37], and the recently discovered iron superconductors [38][39][40][41][42][43] have all exploited the slow and fast variables to considerable success.…”