Magnetic phase diagram of the strongly frustrated quantum spin chain system PbCuSO$_4$(OH)$_2$ in tilted magnetic fields

TL;DR

This study maps the magnetic phase diagram of a frustrated quantum spin chain material under tilted magnetic fields, revealing the persistence of a high-field spin density wave phase and the collapse of an intermediate phase.

Contribution

First detailed phase diagram of PbCuSO$_4$(OH)$_2$ in tilted fields, showing robustness of certain magnetic phases against field orientation changes.

Findings

High field spin density wave-like phase persists in tilted fields.

Intermediate collinear antiferromagnetic phase collapses at moderate angles.

Phase diagram mapped down to 0.2 K and up to 10 T.

Abstract

We report the $\mathbf{H}-T$ phase diagram of $S=1/2$ strongly frustrated anisotropic spin chain material linarite PbCuSO$_4$(OH)$_2$ in tilted magnetic fields up to 10 T and temperatures down to 0.2 K. By means of torque magnetometry we investigate the phase diagram evolution as the magnetic field undergoes rotation in $\mathbf{ba}^{\ast}$ and $\mathbf{bc}$ planes. The key finding is the robustness of the high field spin density wave-like phase, which may persist even as the external field goes orthogonal to the chain direction $\mathbf{b}$. In contrast, the intermediate collinear antiferromagnetic phase collapses at moderate deflection angles with respect to $\mathbf{b}$ axis.