Identification of a Griffiths singularity in a geometrically frustrated antiferromagnet

TL;DR

This paper reports the detection of a Griffiths Phase in a geometrically frustrated antiferromagnet, using thermoremanent magnetization measurements, revealing insights into spin interactions and the effects of oxygen non-stoichiometry.

Contribution

It demonstrates that thermoremanent magnetization is a superior method for identifying Griffiths Phases and shows that the Griffiths Temperature remains unaffected by changes in oxygen stoichiometry.

Findings

Griffiths Phase observed in DyBaCo4O7+δ.

Thermoremanent magnetization effectively identifies the Griffiths Phase.

Griffiths Temperature is invariant despite changes in oxygen non-stoichiometry.

Abstract

We report the observation of a Griffiths Phase in the geometrically frustrated antiferromagnet DyBaCo${_4}$O${_{7+\delta}}$. Its onset is determined using measurements of the thermoremanent magnetization, which is shown to be superior to conventional in-field measurement protocols for the identification of the Griffiths Phase. Within this phase, the temporal relaxation of magnetization exhibits a functional form which is expected for Heisenberg systems, reflecting the nature of spin interactions in this class of materials. Interestingly, the effective Co${^{2+}}$/Co${^{3+}}$ ratio tailored by varying the oxygen non-stoichiometry $\delta$ is only seen to influence the antiferromagnetic ordering temperature ($T{_N}$), leaving the Griffiths Temperature ($T{_G}$) invariant.