Muon Spin Relaxation Investigation of the Spin Dynamics of Geometrically Frustrated Antiferromagnets Y2Mo2O7 and Tb2Mo2O7 Static Critical Behavior of the Spin-Freezing

TL;DR

This study uses muon spin relaxation to explore the spin dynamics and critical behavior of geometrically frustrated pyrochlore antiferromagnets Y2Mo2O7 and Tb2Mo2O7, revealing slow spin fluctuations and a spin-glass-like disordered state.

Contribution

It provides new insights into the spin freezing and low-energy magnetic excitations in pyrochlore antiferromagnets through muon spin relaxation measurements.

Findings

Dramatic slowing down of spin fluctuations near freezing temperatures

Disordered magnetic state similar to spin glass with residual relaxation

High density of low-energy magnetic excitations

Abstract

The spin dynamics of geometrically frustrated pyrochlore antiferromagnets Y2Mo2O7 and Tb2Mo2O7 have been investigated using muon spin relaxation. A dramatic slowing down of the moment fluctuations occurs as one approaches the spin freezing temperatures (TF=22 K and 25 K respectively) from above. Below TF there is a disordered magnetic state similar to that found in a spin glass but with a residual muon spin relaxation rate at low temperatures. These results show that there is a large density of states for magnetic excitations in these systems near zero energy.