Perfect selective orientation of nitrogen vacancy centers in diamond

Nitrogen-vacancy centers in diamond are equally aligned along one of four axes. The precise control of the NV axis is significant for enhancement of a magnetic-field sensitivity. We investigated the alignment of NV centers in a (111)-CVD diamond by optically detected magnetic resonance. more than 99 {\%} of the NV centers is aligned along the [111]-axis [1]. Simulation results using first-principles energetics also demonstrate that the preferential alignment is caused by the nitrogen-atom lone-pair in the [111] direction [2]. We show preliminary results of the preferential alignment of NV centers made by an ion-implantation. Note that other groups reported such an alignment of NV centers [3]. we acknowledge financial support by SCOPE, JST-CREST, KAKENHI, and NICT programs. [1] T. Fukui, et al., Appl. Phys. Express \textbf{7}, 121202 (2014). [2] T. Miyazaki, T. Fukui, et al., arXiv: 1409. 2573 (2014). [3] J. Michl, et al., Appl. Phys. Lett. \textbf{104}, 102407 (2014); M. Lesik, et al., Appl. Phys. Lett. \textbf{104}, 113107 (2014).