Abstract
The nonstoichiometric double perovskite oxide was synthesized by solid-state reaction and its crystal and magnetic structures were investigated by powder x-ray and neutron diffraction. crystallizes in the monoclinic double perovskite structure (general formula ) with space group , where the site is fully occupied by Ni and the ′ site by 19% Ni and 81% Os atoms. Using x-ray absorption spectroscopy an oxidation state was established, suggesting the presence of about 50% paramagnetic () and 50% nonmagnetic () ions at the ′ sites. Magnetization and neutron diffraction measurements on provide evidence for a ferrimagnetic transition at 125 K. The analysis of the neutron data suggests a canted ferrimagnetic spin structure with collinear -spin chains extending along the axis but a noncollinear spin alignment within the plane. The magnetization curve of features a hysteresis with a very high coercive field, , at , which is explained in terms of large magnetocrystalline anisotropy due to the presence of Os ions together with atomic disorder. Our results are encouraging to search for rare-earth-free hard magnets in the class of double perovskite oxides.
2 More- Received 8 February 2018
DOI:https://doi.org/10.1103/PhysRevB.97.184407
©2018 American Physical Society