Nanoscale Magnetic Localization in Exchange Strength Modulated Ferromagnets

Published

August 3, 2018

Author(s)

Brian J Kirby, L. Fallarino, P. Riego, Brian B. Maranville, Casey W. Miller, A. Berger

Abstract

Compositional grading can be used to continuously vary the "local" Curie temperature across the thickness of a ferromagnetic alloy thin film, allowing for a continuously moveable vertical boundary between strongly and weakly magnetized regions. The utility of this interest functionality is largely dependent on the inherent spatial resolution of magnetic properties - specifically the distance over which the magnetic exchange strength behaves locally. To test the degree of localization, we have studied epitaxially grown ferromagnetic CoRu alloy films with Ru concentration that is varied with a triangular waveform at the nanometer scale. Using polarized neutron reflectometry, we show continuous modulation of the local Curie temperature across distance as short as 4.9 nm. Comparison with mean-field simulations of localized spins indicate that non-local magnetic effects are negligible at distances greater 0.6 nm. These results demonstrate that for a compositionally graded system, the local magnetic properties are determined virtually entirely by the corresponding local material properties, down to, and possibly below the nm scale. Since this is demonstrated for an itinerant metallic system, we assert that 1 nm is likely a general upper limit for the onset of locality for virtually any such modulated ferromagnet.

Citation

Physical Review B

Volume

98

Issue

6

Pub Type

Journals

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Citation

, B. , Fallarino, L. , Riego, P. , , B. , , C. and Berger, A. (2018), Nanoscale Magnetic Localization in Exchange Strength Modulated Ferromagnets, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925047 (Accessed October 11, 2025)