Evidence for field induced quantum spin liquid behavior in a spin-1/2 honeycomb magnet

TL;DR

This paper presents evidence that applying a magnetic field to a honeycomb magnet induces a quantum spin liquid state, characterized by fractionalized excitations, supported by experimental observations and theoretical simulations.

Contribution

It provides the first experimental evidence of a field-induced quantum spin liquid in a 3d-based honeycomb magnet, supported by variational Monte Carlo simulations.

Findings

Disordered phase appears between 7.5 T and 10 T magnetic field.

Restoration of crystalline symmetry observed in torque measurements.

Coexistence of magnon excitations and spinon continuum in neutron scattering.

Abstract

One of the most important issues in modern condensed matter physics is the realization of fractionalized excitations, such as the Majorana excitations in the Kitaev quantum spin liquid. To this aim, the 3d-based Kitaev material Na2Co2TeO6 is a promising candidate whose magnetic phase diagram of B // a* contains a field-induced intermediate magnetically disordered phase within 7.5 T < |B| < 10 T. The experimental observations, including the restoration of the crystalline point group symmetry in the angle-dependent torque and the coexisting magnon excitations and spinon-continuum in the inelastic neutron scattering spectrum, provide strong evidence that this disordered phase is a field induced quantum spin liquid with partially polarized spins. Our variational Monte Carlo simulation with the effective K-J1-{\Gamma}-{\Gamma}'-J3 model reproduces the experimental data and further supports this conclusion.