Critical slowing down in the geometrically frustrated pyrochlore antiferromagnet Gd_2Ti_2O_7

TL;DR

This study investigates the critical slowing down of spin fluctuations in the geometrically frustrated pyrochlore antiferromagnet Gd_2Ti_2O_7 using muon spin relaxation, revealing field-dependent relaxation dynamics near the phase transition.

Contribution

It provides experimental evidence of critical slowing down in Gd_2Ti_2O_7 and shows how applied magnetic fields influence spin relaxation times near the transition.

Findings

Relaxation time T_1 is proportional to field at high fields.

T_1 saturates below a crossover field B_c of ~2.5 T at 1.5 K.

Relaxation rate increases near T_m but is suppressed by applied magnetic field.

Abstract

Longitudinal-field muon spin relaxation experiments have been carried out in the paramagnetic state of single-crystal Gd_2Ti_2O_7 just above the phase transition at T_m = 1.0 K. At high applied fields the exponential relaxation time T_1 is proportional to field, whereas T_1 saturates below a crossover field B_c that is ~2.5 T at 1.5 K and decreases as T_m is approached. At low fields the relaxation rate increases markedly as the freezing temperature is approached, as expected for critical slowing down of the spin fluctuations, but the increase is suppressed by applied field. This behavior is consistent with the very long autocorrelation function cutoff time implied by the low value of B_c.