Publications by Roger Johnson

Temperature-induced phase transition from cycloidal to collinear antiferromagnetism in multiferroic Bi0.9Sm0.1FeO3 driven by f-d induced magnetic anisotropy

Physical Review B - Condensed Matter and Materials Physics American Physical Society 95 (2017) 054420-

R Johnson, PA McClarty, DD Khalyavin, P Manuel, P Svedlindh, CS Knee

In multiferroic BiFeO3 a cycloidal antiferromagnetic structure is coupled to a large electric polarization at room temperature, giving rise to magnetoelectric functionality that may be exploited in novel multiferroic-based devices. In this paper, we demonstrate that substituting samarium for 10% of the bismuth ions increases the periodicity of the room-temperature cycloid, and upon cooling to below ∼15 K the magnetic structure tends towards a simple G-type antiferromagnet, which is fully established at 1.5 K. We show that this transition results from f-d exchange coupling, which induces a local anisotropy on the iron magnetic moments that destroys the cycloidal order - a result of general significance regarding the stability of noncollinear magnetic structures in the presence of multiple magnetic sublattices.

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