Absence of induced ferromagnetism in epitaxial uranium dioxide thin films

W. Thomas, F. Wilhelm, Sean Langridge, L. M. Harding, C. Bell, R. Springell, S. Friedemann, Roberto Caciuffo, G. H. Lander

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Recently, Y. Sharma et al. [Adv. Sci. 9, 2203473 (2022)] claimed that thin films (∼20 nm) of UO2 deposited on perovskite substrates exhibit strongly enhanced paramagnetism (called “induced ferromagnetism” by the authors). Moments of up to 3µB/U atom were claimed in magnetic fields of 6 T. We have reproduced such films and, after characterization, have examined them with x-ray circular magnetic dichroism (XMCD) at the uranium M edges, a technique that is element specific. We do not confirm the published results. We find a small increase, as compared to the bulk, in the magnetic susceptibility of UO2 in such films, but the magnetization versus field curves, measured by XMCD, are linear with field and there is no indication of any ferromagnetism. The absence of any anomaly around 30 K (the antiferromagnetic ordering temperature of bulk UO2) in the XMCD signal suggests the films do not order magnetically.
Original languageEnglish
Article number064420
Number of pages6
JournalPhysical Review B
Volume109
Issue number6
DOIs
Publication statusPublished - 22 Feb 2024

Bibliographical note

Publisher Copyright:
© 2024 American Physical Society.

Keywords

  • Uranium
  • Thin film
  • ferromagnetism
  • X-ray diffraction (XRD)
  • XMCD
  • Epitaxial growth

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