Pressure-induced melting of magnetic order and emergence of new quantum state in alpha-RuCl3

TL;DR

This study reveals that applying pressure to alpha-RuCl3 melts its antiferromagnetic order and induces a new quantum state, characterized by a stable, exotic gapped phase resistant to high pressures, advancing understanding of quantum spin liquids.

Contribution

It provides the first high-pressure evidence of melting magnetic order and emergence of a novel quantum state in alpha-RuCl3, a candidate quantum spin liquid material.

Findings

Antiferromagnetic order melts at 0.7 GPa.

Pressure increases transition temperature below Pc.

High-pressure phase exhibits a stable, gapped quantum state.

Abstract

Here we report the observation of pressure-induced melting of antiferromagnetic (AFM) order and emergence of a new quantum state in the honeycomb-lattice halide alpha-RuCl3, a candidate compound in the proximity of quantum spin liquid state. Our high-pressure heat capacity measurements demonstrate that the AFM order smoothly melts away at a critical pressure (Pc) of 0.7 GPa. Intriguingly, the AFM transition temperature displays an increase upon applying pressure below the Pc, in stark contrast to usual phase diagrams, for example in pressurized parent compounds of unconventional superconductors. Furthermore, in the high-pressure phase an unusual steady of magnetoresistance is observed. These observations suggest that the high-pressure phase is in an exotic gapped quantum state which is robust against pressure up to ~140 GPa.