Demonstration of molecular beam epitaxy and a semiconducting band structure for I-Mn-V compounds

T. Jungwirth, V. Novák, X. Martí, M. Cukr, F. Máca, A. B. Shick, J. Mašek, P. Horodyská, P. Němec, V. Holý, J. Zemek, P. Kužel, I. Němec, B. L. Gallagher, R. P. Campion, C. T. Foxon, and J. Wunderlich

Our ab initio theory calculations predict a semiconducting band structure of I-Mn-V compounds. We demonstrate on LiMnAs that high-quality materials with group-I alkali metals in the crystal structure can be grown by molecular beam epitaxy. Optical measurements on the LiMnAs epilayers are consistent with the theoretical electronic structure. Our calculations also reproduce earlier reports of high antiferromagnetic ordering temperature and predict large, spin-orbit-coupling-induced magnetic anisotropy effects. We propose a strategy for employing antiferromagnetic semiconductors in high-temperature semiconductor spintronics [1].

Fig  1. Two branches of the closest relatives of silicon emerging from the "proton transfer" rule. The left-hand branch is obtained by imagining one or two proton transfer from the first to the second atom of the primitive cell; the right-hand branch assumes that one proton is transferred into an empty interstitial space in the lattice. Owing to its isovalent nature, Mn naturally extends the elements from the group-II zinc column.

Fig  2. RHEED image of the LiMnAs film after 60 min of MBE growth. The lines yield evidence of the two-dimensional growth character an expected in-plane crystal symmetry.

Fig  3. Fabry-Pérot interference oscillations of the light back-reflected by the growing LiMnAs film on an InAs substrate plotted as a function of the growth time and wavelength of the detected light. The oscillatory interferences are typical of a semiconductor film.

[1] Phys. Rev. B 83, 035321 (2011), doi: 10.1103/PhysRevB.83.035321.