Anomalous slow dynamics in the metallic helimagnet Gd_{1-x}Y_{x}

TL;DR

This study investigates the slow magnetic dynamics in Gd_{1-x}Y_{x} helimagnet, revealing unique ac-susceptibility behavior and nonlinearity at transition, likely due to weak magnetic anisotropy affecting domain motion or helimagnetic period.

Contribution

It demonstrates that weak magnetic anisotropy in Gd-based helimagnets causes anomalous slow dynamics and nonlinear magnetization, a behavior not seen in similar rare-earth helimagnets.

Findings

Increased imaginary ac-susceptibility in the helimagnetic phase.

Strong nonlinearity of magnetization at T_N.

Anomalous behavior absent in Ho-based helimagnets.

Abstract

Ac-suseptibility measurements were performed in the metallic helimagnet Gd_{1-x}Y_{x} alloy. A remarkable increase of the imaginary part of the ac-suseptibility was observed in the temperature range of the helimagnetic phase. Moreover, a strong nonlinearity of the magnetization was observed at paramagnetic-helimagnetic transition temperature T_{N}. On the other hand, These anomalous behavior were not observed in similar rare-earth helimagnets Ho and Ho_{1-x}Y_{x}. It strongly suggests that the weak magnetic anisotropy of the Gd-moments is responsible for the anomalous slow dynamics in the helimagnetic phase and for the strong nonlinearity of the magnetization at T_{N}. The slow dynamics may result from a chiral-domain motion, or a long-time variation of the period of the helimagnetic structure.