# Detecting spin fractionalization in a spinon Fermi surface spin liquid

## TL;DR

This paper predicts how weak magnetic fields affect spinon excitations in spinon Fermi surface spin liquids, providing testable signatures for experiments like inelastic neutron scattering in candidate materials.

## Contribution

It offers a theoretical prediction of spectral features and experimental signatures of spinon fractionalization under weak magnetic fields in spin liquid candidates.

## Key findings

- Spectral weight shifts in magnetic fields
- Spectral crossing phenomena
- Experimental signatures for neutron scattering

## Abstract

Motivated by the recent proposal of the spinon Fermi surface spin liquids for several candidate materials such as YbMgGaO4, we explore the experimental consequences of the external magnetic fields on this exotic state. Specifically, we focus on the weak field regime where the spin liquid state is well preserved and the spinon remain to be a good description of the magnetic excitations. From the spin-1/2 nature of the spinon excitation, we predict the unique features of the spinon continuum when the weak magnetic field is applied to the system. Due to the small energy scale of the exchange interactions between the local moments in the spin liquid candidate like YbMgGaO4, our proposal for the spectral weight shifts and spectral crossing in the magnetic fields can be immediately tested by inelastic neutron scattering experiments. Several other experimental aspects about the spinon Fermi surface and the spinon excitations are discussed and proposed. Our work provides an experimental scheme to examine the fractionalized spinon excitation and the candidate spin liquid states in YbMgGaO4, the 6H-B phase of Ba3NiSb2O9 and other relevant materials.