Pressure-induced new magnetic phase in Tl(Cu$_{0.985}$Mg$_{0.015}$)Cl$_3$ probed by muon spin rotation

TL;DR

This study uses muon spin rotation to reveal a pressure-induced magnetic phase in Mg-doped TlCuCl3, showing a transition to an oblique antiferromagnetic state at lower pressures than in pure samples.

Contribution

It demonstrates the emergence of a new magnetic phase under pressure in impurity-doped TlCuCl3, expanding understanding of pressure effects on quantum spin gap systems.

Findings

Long-range magnetic order observed at 3.1 kbar

Internal magnetic field saturates around 280 Oe at 4 K

Rearrangement of spins suggests oblique antiferromagnetic phase

Abstract

We carried out zero-field muon-spin-rotation (ZF-$\mu$SR) measurements in hydrostatic pressures in impurity-doped quantum spin gap system Tl(Cu$_{0.985}$Mg$_{0.015}$)Cl$_3$ to investigate microscopic magnetic properties of the pressure-induced phase. The spontaneous muon spin precession, which indicates the existence of a long-range coherent order, is observed in pressures. With decreasing temperature in 3.1 kbar, the internal static magnetic field at the muon sites {\it H}$_{\rm int}$ tends to saturate to 280 Oe around 4 K, however, decreases to 240 Oe at 2.3 K. These results suggest a rearrangement of ordered spins, and we speculate that the oblique antiferromagnetic phase, which is observed in the pressure of 14 kbar on the pure TlCuCl$_3$, appears in the Mg-doped system in lower pressures.