1. R. K. Singh and J. Narayan, Phys. Rev. B 41, 8843 (1990).
2. N. I. Klyui, V. G. Litovchenko, A. N. Luk’yanov, L. V. Neselevskaya, A. V. Sarikov, V. G. Dyskin, U. Kh. Gaziev, Z. S. Settarova, and M. N. Tursunov, Zh. Tekh. Fiz. 76(5), 122 (2006) [Tech, Phys. 51, 654 (2006)].
3. Zh. Zhang and G. Gogos, Phys. Rev. B 69(235432), 1 (2004).
4. Min Han, Yanchun Crong, Jianteng Zhou, et al., Phys. Lett. A 302, 182 (2002).
5. T. E. Itina, J. Hermann, Ph. Delaporte, et al., Appl. Surf. Sci. 208–209, 27 (2003).