Khan Alam1,Rodrigo Ponce-Perez2,3,Kai Sun4,Andrew Foley2,Noboru Takeuchi2,3,Arthur Smith2
King Fahd University of Petroleum and Minerals1,Ohio University2,Universidad Nacional Autonoma de Mexico3,University of Michigan–Ann Arbor4
Khan Alam1,Rodrigo Ponce-Perez2,3,Kai Sun4,Andrew Foley2,Noboru Takeuchi2,3,Arthur Smith2
King Fahd University of Petroleum and Minerals1,Ohio University2,Universidad Nacional Autonoma de Mexico3,University of Michigan–Ann Arbor4
<b>Abstract</b><br/>Interest in studying CrN thin films has been increasing due to their interesting structural[1,2], electronic[3], and magnetic[4] properties. We have investigated the structural phase transition in high-quality CrN thin films grown on MgO(001) substrates using molecular beam epitaxy. Our analysis, which combines cross-sectional transmission electron microscopy and X-ray diffraction, has revealed that the CrN film exhibits an epitaxial relationship with the MgO substrate along three orientations: [100]<sub>CrN</sub>/[100]<sub>MgO</sub>, [110]<sub>CrN</sub>/[110]<sub>MgO</sub>, and [001]<sub>CrN</sub>/[001]<sub>MgO</sub>. These films display tensile strain or compression at the CrN/MgO(001) interface, which gradually relaxes during film growth. Furthermore, our temperature-dependent X-ray diffraction measurements have provided evidence of a first-order structural phase transition. Complementing our experimental findings, we conducted first-principles theoretical calculations to identify a stable model for the CrN/MgO interface. These calculations yielded two possible models for the interface, both of which feature a monolayer of chromium oxide positioned between the CrN and MgO layers.<br/><br/><b>Acknowledgements</b><br/>This work was supported by the Interdisciplinary Research Center for Renewable Energy and Power Systems of King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia under grant No. INRE2216. A.R.S. thank the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering for supporting the research under Award No. DE-FG02-06ER46317. R.P.P. and N.T. thank DGAPA-UNAM projects IN101523 and IN105722, and CONACyT grant A1-S-9070 for partial financial support.<br/><br/><b>References</b><br/>1. K. Alam, S. M. Disseler, W. D. Ratcliff, J. A. Borchers, R. Ponce-Pérez, G. H. Cocoletzi, N. Takeuchi, A. Foley, A. Richard, and D. C. Ingram, Phys. Rev. B <b>96</b>, 104433 (2017).<br/>2. K. Alam, R. Ponce-Pérez, K. Sun, A. Foley, N. Takeuchi, and A. R. Smith, J. Vac. Sci. Technol. A <b>41</b>, 053411 (2023).<br/>3. K. Alam, M. B. Haider, M. F. Al-Kuhaili, K. A. Ziq, and B. U. Haq, Ceram. Int. <b>48</b>, 17352 (2022).<br/>4. K. Alam, R. Ponce-Pérez, K. Sun, A. Foley, N. Takeuchi, and A. R. Smith, J. Vac. Sci. Technol. Vac. Surf. Films <b>39</b>, 063209 (2021).