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The Cr4+ oxidation state with two electrons in the Cr 3d shell is not often observed in perovskite-type oxides, as high pressures and temperatures are generally required to stabilize the octahedral coordination. Herein, we present a comparative study of the novel half-doped perovskite-type chromites Gd0.5Sr0.5CrO3 (GSCO) and Gd0.5Ca0.5CrO3 (GCCO). Fifty percent of the Cr occurs in the Cr4+ oxidation state following high-pressure synthesis at 6 GPa and 1200 °C. The materials were investigated using synchrotron X-ray diffraction, magnetization, heat capacity, and dielectric measurements. The diffraction patterns show that GSCO and GCCO crystallize in orthorhombic (Pbnm) structures with different degrees of local lattice distortion. GSCO exhibits a long-range magnetic order at temperatures of <98 K, accompanied by magnetization reversal, suggesting that the magnetic ground state is ferrimagnetic. In contrast, GCCO displays antiferromagnetic characters at temperatures below approximately 100 K. In addition, GSCO exhibits a crossover between conventional and inverse exchange bias effects at low temperatures (<50 K). This is likely caused by asymmetric exchange Dzyaloshinskii-Moriya interactions between the Cr ions of different valences (+3 and +4). Furthermore, significant magnetoelectric coupling at the onset of the magnetic order is supported by temperature-dependent dielectric measurements.

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• In Copyright
  ©2022 American Physical Society

Keyword: perovskite oxide, chromium, exchange bias effect

Date published: 2022-09-21

Publisher: American Physical Society (APS)

Journal:

• Physical Review B (ISSN: 1550235X) vol. 106 issue. 10 104425

Funding:

• Japan Society for the Promotion of Science JP20H05276
• Japan Society for the Promotion of Science JP22H04601
• Japan Synchrotron Radiation Research Institute 2020A4501
• Japan Synchrotron Radiation Research Institute 2021A1169

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4733

First published URL: https://doi.org/10.1103/physrevb.106.104425

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Updated at: 2024-09-10 12:30:18 +0900

Published on MDR: 2024-09-10 12:30:18 +0900