Anisotropic electronic phase transition in CrN epitaxial thin films

Electronic phase transition in strongly correlated materials is extremely sensitive to the dimensionality and crystallographic orientations. Transition metal nitrides (TMNs) are seldom investigated due to the difficulty in fabricating high-quality and stoichiometric single crystals. In this Letter, we report the epitaxial growth and electronic properties of CrN films grown on different-oriented NdGaO3 (NGO) substrates. Astonishingly, CrN films grown on (110)-oriented NGO substrates maintain a metallic phase, whereas the CrN films grown on (010)-oriented NGO substrates are semiconducting. We attribute the unconventional electronic phase transitions in CrN films to the strain effects. The effective modulation of bandgap by the anisotropic strain triggers the metal-to-insulator transition consequently. This work provides a convenient approach to modify the electronic ground states of functional materials using anisotropic strain and further stimulates the investigations of TMNs.

Automated summary

Electronic phase transition in strongly correlated materials is highly sensitive to dimensionality and crystallographic orientations. Transition metal nitrides (TMNs) have been rarely investigated due to the challenge in fabricating high-quality single crystals with proper stoichiometry. In this study, epitaxial growth and electronic properties of CrN films on different-oriented NdGaO3 (NGO) substrates were reported. Surprisingly, CrN films on (110)-oriented NGO substrates maintain a metallic phase, while the ones grown on (010)-oriented NGO substrates exhibit semiconducting behavior. The unconventional electronic phase transitions in CrN films are attributed to strain effects. Modulation of bandgap by anisotropic strain triggers the metal-to-insulator transition. This work provides a convenient approach to modify electronic ground states of functional materials using anisotropic strain and further promotes the investigation of TMNs.