Regensburg 2022 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 2: Focus Session: Defects and Interfaces in Multiferroics 1

KFM 2.6: Talk

Monday, September 5, 2022, 11:45–12:05, H5

X-ray investigation of a multiferroic YBaCuFeO₅ single crystal — •Arkadiy Simonov¹, Marisa Medarde², and Ruggero Frison³ — ¹ETH Zürich, Zürich, Switzerland — ²Paul Scherrer Institut (PSI), Willigen, Switzerland — ³University of Zürich, Zürich, Switzerland

Recent reports have shown that type-II multiferroic materials can be created using chemical disorder. Disorder frustrates magnetic interaction and induces a magnetic spiral state which breaks the inversion symmetry of the crystal [1]. Such a mechanism is robust since it involves only nearest-neighbor magnetic exchanges and can stabilize the spiral state almost up to room temperature in materials like YBaCuFeO₅. However, due to the complexity of characterizing and controlling chemical disorder, this mechanism is rarely used in practice to design novel multiferroic materials.

In this work we propose single-crystal x-ray diffuse scattering as a method for characterizing disorder. Using YBaCuFeO5 as our model system, we show that diffuse scattering can efficiently probe the local structure induced by chemical disorder. Moreover, when measured at sufficiently high resolution, diffuse scattering is also sensitive to the magnetic phase transition from antiferromagnetic to spiral state of the YBaCuFeO₅. This is unusual, and likely indicates that atomic relaxations induced by this transition are larger than the values observed in typical type-II multiferroics.

[1] M. Morin et al. Nat. Comms. 7, (2016): 133758.