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 Cr2O3 layer grown on the α-Al2O3(0001) substrate isostructural to Cr2O3 and determined T N of the fabricated films. We varied the sputtering power for the Cr2O3 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.