Doping evolution of the electronic specific heat coefficient in slightly-doped La2-xSrxCuO4 single crystals

TL;DR

This study investigates how the electronic specific heat coefficient gamma varies with doping in La2-xSrxCuO4 single crystals, revealing finite electronic states even in the antiferromagnetic regime where localization occurs.

Contribution

It provides detailed doping dependence of gamma in LSCO, showing finite electronic density of states in the antiferromagnetic regime, challenging the insulator classification.

Findings

Gamma increases with doping.

Finite gamma in the AF regime indicates non-zero DOS.

System remains metallic-like despite AF order.

Abstract

Detailed doping dependence of the electronic specific heat coefficient gamma is studied for La2-xSrxCuO4 (LSCO) single crystals in the slightly-doped regime. We find that gamma systematically increases with doping, and furthermore, even for the samples in the antiferromagnetic (AF) regime, gamma already acquires finite value and grows with x. This suggests that finite electronic density of states (DOS) is created in the AF regime where the transport shows strong localization at low temperatures, and this means the system is not a real insulator with a clear gap even though it still keeps long range AF order.