Magnetic skin effect in Pb (Fe1/2 Nb1/2) O3

Giles-Donovan, N., Hillier, A.D., Ishida, K., Hampshire, B.V., Giblin, S.R. ORCID: https://orcid.org/0000-0003-1876-8619, Roessli, B., Gehring, P.M., Xu, G., Li, X., Luo, H., Cochran, S. and Stock, C. 2024. Magnetic skin effect in Pb (Fe1/2 Nb1/2) O3. Journal of Physics: Condensed Matter 36 (43) , 435802. 10.1088/1361-648X/ad6523 Item availability restricted.

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Abstract

Relaxor-ferroelectrics display exceptional dielectric properties resulting from the underlying random dipolar fields induced by strong chemical inhomogeneity. An unusual structural aspect of relaxors is a skin-effect where the near-surface region in single crystals exhibit structures and critical phenomena that differ from the bulk. Relaxors are unique in that this skin effect extends over a macroscopic lengthscale of ∼100  whereas usual surface layers only extend over a few unit cells (or ∼nm). We present a muon spectroscopy study of Pb(Fe Nb )O3 (PFN) which displays ferroelectric order, including many relaxor-like dielectric properties such as a frequency broadened dielectric response, and antiferromagnetism with spatially short-range polar correlations and hence can be termed a multiferroic. In terms of the magnetic behavior determined by the Fe3+ ( , L ≈ 0) ions, PFN has been characterized as a unique example of a 'cluster spin-glass'. We use variable momentum muon spectroscopy to study the depth dependence of the slow magnetic relaxations in a large 1 cm3 crystal of PFN. Zero-field positive muon spin relaxation is parameterized using a stretched exponential, indicative of a distribution of relaxation rates of the Fe3+ spins. This bandwidth of frequencies changes as a function of muon momentum, indicative of a change in the Fe3+ relaxation rates as a function of muon implantation depth in our single crystal. Using negative muon elemental analysis, we find small-to-no measurable change in the Fe3+/Nb5+ concentration with depth implying that chemical concentration alone cannot account for the change in the relaxational dynamics. PFN displays an analogous magnetic skin effect reported to exist in the structural properties of relaxor-ferroelectrics.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Physics and Astronomy
Publisher:	IOP Publishing
ISSN:	0953-8984
Date of First Compliant Deposit:	6 September 2024
Date of Acceptance:	18 July 2024
Last Modified:	07 Nov 2024 20:00
URI:	https://orca.cardiff.ac.uk/id/eprint/171856

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