The spin-splitting energies in strained bulk wurtzite aluminum nitride (AlN) are studied using the linear combination of atomic orbital method. It is found that strain and crystal field induce not only a linear-k (αwz) but also two cubic-k terms (γ' and λ') in the two-band k \cdot p Hamiltonian HSO(k) = (αwz-γ'k\|2 + λ'kz2)(σxky-σykx) + HSO0, where HSO0 = (-γ0k\|2 + λ0kz2) (σxky-σykx) is for ideal wurtzite and generates a cone-shaped minimum-spin-splitting (MSS) surface. As biaxial strain increases, the shape of the MSS surface changes from a hexagonal hyperboloid of two sheets in unstrained AlN to a hexagonal cone, and eventually becomes a hyperboloid of one sheet.
關聯:
Journal of the Physical Society of Japan 79(9), 093705(4pages)