Scale-Invariance of a Spin Liquid in High Magnetic Fields

TL;DR

This study investigates the magnetic response of RuCl₃ under high magnetic fields, revealing scale-invariant anisotropy that supports the existence of a spin liquid state driven by exchange frustration.

Contribution

It provides experimental evidence of scale-invariance in magnetic anisotropy in RuCl₃, highlighting the role of exchange frustration in stabilizing a spin liquid.

Findings

Magnetic field and temperature effects are independent of exchange energy.

Emergent scale-invariant magnetic anisotropy observed.

Supports the presence of a spin liquid state in RuCl₃.

Abstract

In RuCl$_3$, inelastic neutron scattering and Raman spectroscopy reveal a continuum of non-spin-wave excitations that persists to high temperature, suggesting the presence of a spin liquid state on a honeycomb lattice. In the context of the Kitaev model, magnetic fields introduce finite interactions between the elementary excitations, and thus the effects of high magnetic fields - comparable to the spin exchange energy scale - must be explored. Here we report measurements of the magnetotropic coefficient - the second derivative of the free energy with respect to magnetic field orientation - over a wide range of magnetic fields and temperatures. We find that magnetic field and temperature compete to determine the magnetic response in a way that is independent of the large intrinsic exchange interaction energy. This emergent scale-invariant magnetic anisotropy provides evidence for a high degree of exchange frustration that favors the formation of a spin liquid state in RuCl$_3$.