Charge order, metallic behavior and superconductivity in La_{2-x}Ba_xCuO_4 with x=1/8

TL;DR

This study investigates the optical properties of La_{2-x}Ba_xCuO_4 with x=1/8, revealing charge order and metallic behavior, but no bulk superconductivity, with spectral weight shifting to high frequencies below 60 K.

Contribution

It provides detailed optical measurements showing charge order effects and spectral weight redistribution in La_{2-x}Ba_xCuO_4, highlighting differences from superconducting cuprates.

Findings

Spectral weight shifts to high frequency below 60 K

Absence of bulk superconducting condensate

Charge stripe order influences optical properties

Abstract

The ab-plane optical properties of a cleaved single crystal of La_{2-x}Ba_xCuO_4 for x=1/8 (T_c ~ 2.4 K) have been measured over a wide frequency and temperature range. The low-frequency conductivity is Drude-like and shows a metallic response with decreasing temperature. However, below ~ 60 K, corresponding to the onset of charge-stripe order, there is a rapid loss of spectral weight below about 40 meV. The gapping of single-particle excitations looks surprisingly similar to that observed in superconducting La_{2-x}Sr_{x}CuO_4, including the presence of a residual Drude peak with reduced weight; the main difference is that the lost spectral weight moves to high, rather than zero, frequency, reflecting the absence of a bulk superconducting condensate.