# Resonant x-ray scattering reveals possible disappearance of magnetic order under hydrostatic pressure in the Kitaev candidate $\gamma$-Li$_2$IrO$_3$

## TL;DR

This study uses resonant x-ray scattering to show that applying hydrostatic pressure to $ ext{γ}$-Li$_2$IrO$_3$ causes an abrupt loss of its spiral magnetic order at 1.5 GPa, indicating a pressure-induced transition to a different ground state.

## Contribution

First direct observation of the sudden disappearance of magnetic order in $ ext{γ}$-Li$_2$IrO$_3$ under pressure using resonant x-ray scattering, revealing a critical pressure-induced phase transition.

## Key findings

- Magnetic spiral order vanishes abruptly at 1.5 GPa.
- No change in lattice symmetry at the transition.
- Emergence of a possible nonmagnetic ground state under pressure.

## Abstract

Honeycomb iridates such as $\gamma$-Li$_2$IrO$_3$ are argued to realize Kitaev spin-anisotropic magnetic exchange, along with Heisenberg and possibly other couplings. While systems with pure Kitaev interactions are candidates to realize a quantum spin liquid ground state, in $\gamma$-Li$_2$IrO$_3$ it has been shown that the balance of magnetic interactions leads to the incommensurate spiral spin order at ambient pressure below 38 K. We study the fragility of this state in single crystals of $\gamma$-Li$_2$IrO$_3$ using resonant x-ray scattering (RXS) under applied hydrostatic pressures of up to 3.0 GPa. RXS is a direct probe of the underlying electronic order, and we observe the abrupt disappearance of the $q$=(0.57, 0, 0) spiral order at a critical pressure $P_c = 1.5\ $GPa with no accompanying change in the symmetry of the lattice. This dramatic disappearance is in stark contrast with recent studies of $\beta$-Li$_2$IrO$_3$ that show continuous suppression of the spiral order in magnetic field; under pressure, a new and possibly nonmagnetic ground state emerges.