Pressure dependence of the magnetic order in CrAs: a neutron diffraction investigation

TL;DR

This neutron diffraction study investigates how pressure affects the magnetic order in CrAs, revealing that magnetic moments decrease and magnetic peak widths vary near the pressure where superconductivity emerges, indicating competing phases.

Contribution

The paper provides detailed experimental data on the pressure evolution of magnetic order in CrAs, highlighting the persistence of magnetic structure up to critical pressure and its interplay with superconductivity.

Findings

Magnetic order persists under pressure up to 0.7 GPa.

Magnetic moments decrease significantly near the critical pressure.

Magnetic Bragg peak widths peak near the onset of superconductivity.

Abstract

The suppression of magnetic order with pressure concomitant with the appearance of pressure- induced superconductivity was recently discovered in CrAs. Here we present a neutron diffraction study of the pressure evolution of the helimagnetic ground-state towards and in the vicinity of the superconducting phase. Neutron diffraction on polycrystalline CrAs was employed from zero pressure to 0.65 GPa and at various temperatures. The helimagnetic long-range order is sustained under pressure and the magnetic propagation vector does not show any considerable change. The average ordered magnetic moment is reduced from 1.73(2) {\mu}B at ambient pressure to 0.4(1) {\mu}B close to the critical pressure Pc=0.7 GPa, at which magnetic order is completely suppressed. The width of the magnetic Bragg peaks strongly depends on temperature and pressure, showing a maximum in the region of the onset of superconductivity. We interpret this as associated with competing ground-states in the vicinity of the superconducting phase.