Electronic states of a correlated material can be effectively modified by structural variations delivered from a single-crystal substrate. In this paper, we show that the CrN films grown on MgO (001) substrates have a (001) orientation, whereas the CrN films on $\alpha \text{−}{\mathrm{Al}}_2{\mathrm{O}}_3$ (0001) substrates are oriented along the (111) direction parallel to the surface normal. Transport properties of CrN films are remarkably different depending on crystallographic orientations. The critical thickness for the metal-insulator transition in CrN 111 films is significantly larger than that of CrN 001 films. In contrast to CrN 001 films without apparent defects, scanning transmission electron microscopy results reveal that CrN 111 films exhibit strain-induced structural defects, e.g., the periodic horizontal twinning domains, resulting in an increased electron scattering facilitating an insulating state. Understanding the key parameters that determine the electronic properties of ultrathin conductive layers is highly desirable for future technological applications.

中文翻译：

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CrN（111）薄膜中的结构孪生诱导绝缘相

可以通过从单晶衬底传递的结构变化来有效地修改相关材料的电子状态。在本文中，我们表明在MgO（001）衬底上生长的CrN膜具有（001）取向，而在$\alpha \text{-}{铝}_2{\mathrm{Ø}}_3$（0001）个基板沿着与表面法线平行的（111）方向取向。CrN薄膜的传输特性根据晶体学取向而显着不同。CrN 111膜中的金属-绝缘体过渡的临界厚度明显大于CrN 001膜的临界厚度。与没有明显缺陷的CrN 001薄膜相反，扫描透射电子显微镜结果表明CrN 111薄膜表现出应变诱导的结构缺陷，例如周期性的水平孪晶畴，从而导致电子散射增加，从而促进了绝缘状态。对于将来的技术应用，非常需要了解决定超薄导电层电子特性的关键参数。