Domain and domain-wall nuclear magnetic resonance of¹⁶⁵Ho in (Gd,Y)Fe₂

Abstract

Spin-echo NMR measurements have been made, at liquid-helium temperatures, on 165Ho in the ferrimagnetic alloy series Ho0.03GdxY0.97-xFe2. Distinct spectra originating in domains and domain walls have been observed, both showing a non-linear variation of the hyperfine field with x. Results are analysed in terms of a model involving a non-linear dependence of the transferred hyperfine field from iron atoms on the number of gadolinium neighbours. The characteristics of the domain-wall resonances suggest that they originate from coupled nuclear-localised magnon modes.