Magnetic properties of the helimagnet Cr1/3NbS2 observed by muSR

TL;DR

This study uses muSR to investigate the magnetic phase transition and low-temperature magnetic structure modifications in the chiral helimagnet Cr1/3NbS2, revealing a structural influence on magnetic ordering.

Contribution

It provides new insights into the low-temperature magnetic structure changes and suggests a structural transition affecting magnetic order in Cr1/3NbS2.

Findings

Detection of a transition from paramagnetic to helical magnetic order.

Observation of enhanced muon precession frequency below 50K.

Proposal of a longer magnetic helicity period at low temperatures.

Abstract

We have performed muon spin rotation/relaxation (muSR) measurements on single crystals of the chiral helimagnet Cr1/3NbS2 at zero to low magnetic field. The transition from the paramagnetic to helical magnetically ordered phase at zero field is marked by the onset of a coherent oscillation of the zero-field muon spin polarization below a critical temperature Tc. An enhancement of the muon spin precession frequency is observed below T ~ 50K, where anomalous behavior has been observed in bulk transport measurements. The enhanced precession frequency indicates a low-temperature modification of the helical magnetic structure. A Landau free energy analysis suggests that the low-temperature change in the magnetic structure is caused by a structural change, whereas the magnetic order above Tc is the result of an attractive interaction between the ferromagnetic moment induced by the applied field and the magnetic moments of the helical structure. We also suggest a longer periodicity of helicity below T ~ 50K, which can be verified by neutron scattering.