Coupling of Magnetic Orders in La2CuO4+x

TL;DR

This study uses muon spin rotation to investigate magnetic orders in lightly oxygen-doped La2CuO4, revealing a coupling between antiferromagnetism and an additional magnetic order that decouples at higher temperatures.

Contribution

It demonstrates the presence of a second magnetic order coupled to antiferromagnetism in La2CuO4+x and explores how doping affects muSR detection of magnetism.

Findings

Detection of a second magnetic order coupled to antiferromagnetism at low temperatures.

Decoupling of magnetic orders at higher temperatures.

Doping reduces muSR's ability to detect time-reversal symmetry breaking.

Abstract

High transverse magnetic field and zero field muon spin rotation and relaxation measurements have been carried out in a lightly oxygen-doped high-Tc parent compound La2CuO4 in a temperature range from 2 K to 300 K. As in the stoichiometric compound, muon spin rotation spectra reveal, along with the antiferromagnetic local field, the presence of an additional source of magnetic field at the muon. The results indicate that this second magnetic order is driven by the antiferromagnetism at low temperature but the two magnetic orders decouple at higher temperature. The ability of muSR to detect this additional magnetism deteriorates with doping, thus rendering the technique impotent to reveal time-reversal symmetry breaking in superconductors.