Neutron Diffraction Study of the Pressure-Induced Magnetic Ordering in the Spin Gap System TlCuCl$_3$

TL;DR

This study uses neutron diffraction to explore how hydrostatic pressure induces magnetic ordering in the spin gap system TlCuCl$_3$, revealing the closing of the spin gap and determining the resulting spin structure.

Contribution

It provides the first detailed neutron diffraction analysis of pressure-induced magnetic ordering and spin structure in TlCuCl$_3$, showing how pressure affects the spin gap.

Findings

Magnetic Bragg reflections appear below 16.9 K at 1.48 GPa.

The spin gap closes under applied pressure.

The spin structure of the ordered state was determined.

Abstract

Neutron elastic scattering measurements have been performed under the hydrostatic pressure in order to investigate the spin structure of the pressure-induced magnetic ordering in the spin gap system TlCuCl$_3$. Below the ordering temperature $T_{\rm N}=16.9$ K for the hydrostatic pressure $P=1.48$ GPa, magnetic Bragg reflections were observed at the reciprocal lattice points ${\mib Q}=(h, 0, l)$ with integer $h$ and odd $l$, which are equivalent to those points with the lowest magnetic excitation energy at ambient pressure. This indicates that the spin gap closes due to the applied pressure. The spin structure of the pressure-induced magnetic ordered state for $P=1.48$ GPa was determined.