NMR study on the local structure in La-based high-Tc cuprates

TL;DR

This study uses Cu-NMR to detect a local, incoherent LTT structural phase in La-based high-Tc cuprates below 50 K, revealing a possible link to superconductivity suppression near x=1/8.

Contribution

First direct evidence of incoherent LTT structure in La-based cuprates using NMR, highlighting its potential influence on superconductivity.

Findings

Incoherent LTT structure appears below 50 K in La2-xSrxCuO4.

The LTT phase may contribute to the suppression of superconductivity near x=1/8.

No macroscopic LTT transition observed in these samples.

Abstract

To date, there has been no evidence for the macroscopic structural phase transition to the low temperature tetragonal structure (LTT) with a space group P42/ncm in high-TC cuprate of rare earth-free La2-xSrxCuO4 (LSCO). By investigating Cu-NMR on single crystals, we have found that spatially incoherent LTT structure emerges below 50 K in the sample with x=0.12. This incoherent structure is considered to play a key role for the slight depression of the superconductivity around x=1/8.