Impurity Effects on the Flux Phase Quantum Critical Point Scenario

TL;DR

This paper investigates how impurities like Zn affect the pseudogap phase and quantum critical point in high-temperature superconductors, finding that impurity substitution suppresses T_c but leaves the pseudogap and quantum critical point largely unchanged.

Contribution

It provides a theoretical explanation for impurity effects on the flux phase quantum critical point using a 1/N expansion of the t-J model, aligning with experimental observations.

Findings

Impurity substitution suppresses T_c without affecting the pseudogap onset.

The pseudogap phase and quantum critical point are robust against impurities.

Magnetic field effects are also consistent with a flux phase quantum critical point scenario.

Abstract

Impurity substitution of Zn in La-214 and (Y,Ca)-123 high-T_c superconductors suppresses T_c but does not affect appreciably the onset of the pseudogap phase in the underdoped region nor optimal doping or the position of the inferred quantum critical point. Based on a 1/N expansion of the t-J model we explain these findings as well as the similar dependence on a magnetic field in terms of a quantum critical point scenario where a flux phase causes the pseudogap.