Single-ion anisotropy in Mn-doped diluted magnetic semiconductors

Motivated by recent developments in spintronics, we propose an explanation of the single-ion anisotropy of Mn-doped diluted magnetic semiconductors using as an example high-quality ZnO:Mn thin films for which $X$-band electron-paramagnetic-resonance studies were performed. We derive an analytic formula for the axial parameter $D$ and we prove its validity by the exact diagonalization method. We demonstrate a quantitative agreement between the experimental data and our model. These results bring insights into a long-standing problem of single-ion anisotropy in magnetic solids.

Figure 1

$X$-band EPR spectra taken on ${\text{Zn}}_{1-x}{\text{Mn}}_x\text{O}$ films with different Mn content at 6 K for $H\parallel c$ and $H\perp c$.