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Local structure distortion and spin Hamiltonian parameters of oxide-diluted magnetic semiconductor Mn-doped ZnO
Yang Zi-Yuan(杨子元)
Chin. Phys. B, 2009, 18 (3):
1253-1260.
DOI: 10.1088/1674-1056/18/3/069
The local structure distortion, the spin Hamiltonian (SH) parameters, and the electric fine structure of the ground state for Mn$^{2+}$(3d$^{5})$ ion in ZnO crystals are systematically investigated, where spin--spin (SS), spin--other--orbit (SOO) and orbit--orbit (OO) magnetic interactions, besides the well-known spin--orbit (SO) coupling, are taken into account for the first time, by using the complete diagonalization method. The theoretical results of the second-order zero-field splitting (ZFS) parameter $D$, the fourth-order ZFS parameter ($a$-$F$), the Zeeman $g$-factors: $g_{//}$ and $g_{\bot}$, and the energy differences of the ground state: $\delta_{1}$ and $\delta_{2}$ for Mn$^{2+}$ in Mn$^{2+}$: ZnO are in good agreement with experimental measurements when the three O$^{2-}$ ions below the Mn$^{2+}$ ion rotate by 1.085$^\circ$ away from the [111]-axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Mn$^{2+}$ ions in Mn$^{2+}$: ZnO crystals. It is found for Mn$^{2+}$ ions in Mn$^{2+}$: ZnO crystals that although the SO mechanism is the most important one, the contributions to the SH parameters, made by other four mechanisms, i.e. SS, SOO, OO, and SO$\sim$SS$\sim$SOO$\sim$OO mechanisms, are significant and should not be omitted, especially for calculating ZFS parameter $D$.
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