Formation of pseudo-morphic domain in Cr₂O₃(0001) epitaxial film grown on α-Al₂O₃(0001) and its effect on Néel temperature

Abstract To address the issue of the impact of the epitaxial strain on the Néel temperature T N , we investigated the formation of the epitaxial domain in the Cr 2 O 3 layer grown on the α -Al 2 O 3 (0001) substrate isostructural to Cr 2 O 3 and determined T N of the fabricated films. We varied the sputtering power for the Cr 2 O 3 growth from 10 W to 40 W to alter the strain condition of the epitaxial film. When the sputtering power is 10 W, the single epitaxial domain is formed, whereas the pseudo-morphic and relaxed domains coexist for the sputtering power above 20 W. T N decreased from about 271 K to below 252 K accompanied by the formation of the two types of epitaxial domains. The lattice parameters of the pseudo-morphic domain are beyond the elastic deformation approximation adopted in the theoretical approaches, suggesting that the correlation between the T N value and the microstructure also goes beyond the existing theoretical framework.