Finite-temperature phase diagram of nonmagnetic impurities in high-temperature superconductors using a d=3 tJ model with quenched disorder

TL;DR

This study models nonmagnetic impurities in high-temperature superconductors using a 3D tJ Hamiltonian with quenched disorder, revealing how impurity concentration affects magnetic and superconducting phases at finite temperatures.

Contribution

It introduces a position-space renormalization-group approach to analyze the phase diagram of a disordered tJ model, highlighting impurity effects on magnetic and superconducting phases.

Findings

Superconducting-like spin-singlet phase is destroyed for impurity concentration p > 0.05.

Antiferromagnetic order is enhanced away from half-filling with impurities.

Antiferromagnetic phase near half-filling remains robust up to p > 0.40.

Abstract

We study a quenched disordered d=3 tJ Hamiltonian with static vacancies as a model of nonmagnetic impurities in high-Tc materials. Using a position-space renormalization-group approach, we calculate the evolution of the finite-temperature phase diagram with impurity concentration p, and find several features with close experimental parallels: away from half-filling we see the rapid destruction of a spin-singlet phase (analogous to the superconducting phase in cuprates) which is eliminated for p > 0.05; in the same region for these dilute impurity concentrations we observe an enhancement of antiferromagnetism. The antiferromagnetic phase near half-filling is robust against impurity addition, and disappears only for p > 0.40.