Evolution of the electronic state through the reduction annealing in electron-doped Pr_1.3-x_La_0.7_Ce_x_CuO_4+delta_ (x=0.10) single crystals: Antiferromagnetism, Kondo effect and superconductivity

TL;DR

This study investigates how reduction annealing transforms the electronic state in electron-doped Pr_1.3-x_La_0.7_Ce_x_CuO_4+delta_ single crystals, revealing a transition from localized antiferromagnetic behavior to metallic and superconducting states.

Contribution

It demonstrates the evolution of electronic states due to annealing in T'-structured cuprates, linking oxygen removal to the emergence of superconductivity.

Findings

Reduction annealing changes carriers from localized to metallic.

Superconductivity appears after removing excess oxygen.

Kondo effect observed in the metallic state.

Abstract

The evolution of the electronic state through the reduction annealing has been investigated in electron-doped Pr_1.3-x_La_0.7_Ce_x_CuO_4+delta_ (x=0.10) single crystals with the so-called T' structure. From the ab plane and c axis electrical resistivity measurements in magnetic fields, it has been found that, through the reduction annealing, the strongly localized state of carriers accompanied by the antiferromagnetic (AF) pseudogap in the as-grown crystal changes to a metallic state bringing about the Kondo effect without AF pseudogap and to a superconducting state. These results are able to be understood in terms of a model based on the strong electron correlation. The complete removal of excess oxygen in the T'-cuprates is expected to result in the appearance of superconductivity in a wide range of the Ce concentration including the parent compound of x=0.