Electron-Spin Resonance ofK2ZnF4:Mn2+

Electron-spin-resonance (ESR) measurements at 24 GHz have been made on single crystals of ${\mathrm{K}}_{2}$Zn${\mathrm{F}}_{4}$ doped with Mn. The spectra obtained in these measurements correspond to ${\mathrm{Mn}}^{2+}$ in the ${\mathrm{Zn}}^{2+}$ sites (point group $\frac{4}{\mathrm{mmm}}$)) in this material. The measured values of the spin-Hamiltonian parameters corresponding to the fine and hyperfine structure are ${g}_{\ensuremath{\parallel}}=2.0030$, ${g}_{\ensuremath{\perp}}=2.0028$, $A=\ensuremath{-}88.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$, $B=\ensuremath{-}89.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$, $D=36.0\ifmmode\times\else\texttimes\fi{}{10}^{4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$, $a=5.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$, and $F=1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$. In addition, the transferred hyperfine parameters were obtained from the ESR measurements. The measured values of these parameters, which result from interactions between the ${\mathrm{Mn}}^{2+}$ $3d$ electrons and ${\mathrm{F}}^{\ensuremath{-}}$ and which refer to the four equivalent nearest-neighbor ${\mathrm{F}}^{\ensuremath{-}}$ ions in the (001) plane (type I) and the two equivalent nearest-neighbor ${\mathrm{F}}^{\ensuremath{-}}$ ions along the forfold axis (type II), are ${A}_{s}^{\mathrm{I}}=18.1$, ${A}_{s}^{\mathrm{II}}=14.9$, ${A}_{\ensuremath{\sigma}}^{\mathrm{I}}0.4$, ${A}_{\ensuremath{\sigma}}^{\mathrm{II}}\ensuremath{-}\frac{1}{2}{A}_{\ensuremath{\pi}}^{\mathrm{II}}=0.3$, and ${A}_{\ensuremath{\pi}}^{\mathrm{I}}\ensuremath{\approx}0$, where the subscripts $s$, $\ensuremath{\sigma}$, and $\ensuremath{\pi}$ refer to $s$, ${p}_{\ensuremath{\sigma}}$, and ${p}_{\ensuremath{\pi}}$ electronic bonding, respectively, and all quantities are in units of ${10}^{\ensuremath{-}4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$. From these superhyperfine parameters, the fractions of unpaired spin densities were calculated.