Investigation of the magnetic ground state of GaV$_4$S$_8$ using powder neutron diffraction

TL;DR

This study investigates the magnetic ground state of GaV$_4$S$_8$, revealing a transition from paramagnetic to cycloidal and ferromagnetic-like states, with detailed neutron diffraction analysis of magnetic structures at various temperatures.

Contribution

The paper provides the first detailed neutron diffraction analysis of the magnetic structures in GaV$_4$S$_8$, including the commensurate and incommensurate phases and their magnetic configurations.

Findings

Transition from paramagnetic to cycloidal state below 13 K.

Identification of a ferromagnetic-like state below 6 K with specific magnetic moments.

Detailed analysis of cycloidal magnetic structure in the incommensurate phase.

Abstract

The magnetic ground state of polycrystalline N\'eel skyrmion hosting material GaV$_4$S$_8$ has been investigated using ac susceptibility and powder neutron diffraction. In the absence of an applied magnetic field GaV$_4$S$_8$ undergoes a transition from a paramagnetic to a cycloidal state below 13~K and then to a ferromagnetic-like state below 6~K. With evidence from ac susceptibility and powder neutron diffraction, we have identified the commensurate magnetic structure at 1.5 K, with ordered magnetic moments of $0.23(2)~\mu_{\mathrm{B}}$ on the V1 sites and $0.22(1)~\mu_{\mathrm{B}}$ on the V2 sites. These moments have ferromagnetic-like alignment but with a 39(8)$^{\circ}$ canting of the magnetic moments on the V2 sites away from the V$_4$ cluster. In the incommensurate magnetic phase that exists between 6 and 13 K, we provide a thorough and careful analysis of the cycloidal magnetic structure exhibited by this material using powder neutron diffraction.