Absence of magnetic order in Yb3Ga5O12: relation between phase transition and entropy in geometrically frustrated materials

TL;DR

This study reveals that the sharp specific heat peak in Yb3Ga5O12 does not indicate magnetic order but reflects increased dynamical correlations, highlighting the complex relationship between entropy release and phase transitions in frustrated magnets.

Contribution

It demonstrates that the lambda anomaly in Yb3Ga5O12 is due to magnetic correlations, not a phase transition, challenging traditional interpretations in frustrated magnetic systems.

Findings

The lambda anomaly does not correspond to magnetic ordering.

A broad hump in specific heat indicates other magnetic phenomena.

Long-range order requires significant entropy release at transition.

Abstract

From muon spin relaxation spectroscopy experiments, we show that the sharp peak (lambda type anomaly) detected by specific heat measurements at 54 mK for the ytterbium gallium garnet compound, Yb3Ga5O12, does not correspond to the onset of a magnetic phase transition, but to a pronounced building up of dynamical magnetic pair-correlations. Beside the lambda anomaly, a broad hump is observed at higher temperature in the specific heat of this garnet and other geometrically frustrated compounds. Comparing with other frustrated magnetic systems we infer that a ground state with long-range order is reached only when at least 1/4-1/3 of the magnetic entropy is released at the lambda transition.