Emergence of superconductivity from the dynamically heterogeneous insulating state in La_{2-x}Sr_{x}CuO_{4}

TL;DR

This study investigates how superconductivity emerges from an insulating state in La_{2-x}Sr_{x}CuO_{4} by examining low-temperature magnetoresistance, revealing coexistence of charge glass behavior and superconducting fluctuations near the superconductor-insulator transition.

Contribution

It provides new insights into the coexistence of charge glass behavior and superconducting fluctuations across the superconductor-insulator transition in LSCO.

Findings

Charge glass behavior is suppressed with doping.

Superconducting fluctuations coexist with insulating charge order.

Charge order quenches superconducting fluctuations at low temperatures.

Abstract

A central issue for copper oxides is the nature of the insulating ground state at low carrier densities and the emergence of high-temperature superconductivity from that state with doping. Even though this superconductor-insulator transition (SIT) is a zero-temperature transition, measurements are not usually carried out at low temperatures. Here we use magnetoresistance to probe both the insulating state at very low temperatures and the presence of superconducting fluctuations in La_{2-x}Sr_{x}CuO_{4}(LSCO) films, for doping levels that range from the insulator to the superconductor (x=0.03-0.08). We observe that the charge glass behavior, characteristic of the insulating state, is suppressed with doping, but it coexists with superconducting fluctuations that emerge already on the insulating side of the SIT. The unexpected quenching of the superconducting fluctuations by the competing charge order at low temperatures provides a new perspective on the mechanism for the SIT.