Change of the Ground State upon Hole Doping Unveiled by Ni Impurity in High-$T_{\rm c}$ Cuprates

TL;DR

This study reveals how the electronic ground state in high-$T_c$ cuprates transitions from magnetic order to metallic behavior with Kondo effect as hole doping increases, involving phase separation.

Contribution

It uncovers the change in ground state upon hole doping in cuprates with Ni impurity, highlighting phase separation and the evolution from magnetic to metallic states.

Findings

Ground state shifts from magnetic order to metallic with Kondo effect as doping increases.

Phase separation occurs near the boundary between magnetic and metallic phases.

Ni impurity influences the electronic ground state and phase behavior.

Abstract

The electronic ground state in high-$T_{\rm c}$ cuprates where the superconducting state is suppressed by Ni substitution has been investigated in La$_{2-x}$Sr$_x$Cu$_{1-y}$Ni$_y$O$_4$ from the specific heat and muon spin relaxation measurements. It has been found that the ground state changes from a magnetically ordered state with the strong hole-trapping by Ni to a metallic state with the Kondo effect of Ni with increasing hole-concentration. Moreover, the analysis of the results has revealed that a phase separation into the magnetically ordered phase and the metallic phase occurs around the boundary of two phases.