Pressure-Induced Magnetic Quantum Phase Transition in Gapped Spin System KCuCl3

TL;DR

This study investigates how applying pressure to the gapped spin system KCuCl3 induces a quantum phase transition from a non-magnetic to an antiferromagnetic state, revealing pressure-tuned magnetic properties.

Contribution

It provides experimental evidence of pressure-induced quantum phase transition in a three-dimensional coupled spin dimer system, detailing how pressure affects magnetic interactions and the spin gap.

Findings

Spin gap decreases with increasing pressure.

Quantum phase transition occurs at approximately 8.2 kbar.

Magnetic Bragg reflections confirm the transition to an antiferromagnetic state.

Abstract

Magnetization and neutron elastic scattering measurements under a hydrostatic pressure were performed on KCuCl3, which is a three-dimensionally coupled spin dimer system with a gapped ground state. It was found that an intradimer interaction decreases with increasing pressure, while the sum of interdimer interactions increases. This leads to the shrinkage of spin gap. A quantum phase transition from a gapped state to an antiferromagnetic state occurs at Pc ? 8.2 kbar. For P > P c, magnetic Bragg reflections were observed at reciprocal lattice points equivalent to those for the lowest magnetic excitation at zero pressure. This confirms that the spin gap decreases and closes under applied pressure.