Ultrahigh field electron cyclotron resonance absorption in In 1 − x Mn x As films

We have carried out an ultrahigh-field cyclotron resonance study of n-type ${\mathrm{In}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$ films, with Mn composition x ranging from 0% to 12%, grown on GaAs by low-temperature molecular-beam epitaxy. We observe that the electron cyclotron resonance peak shifts to lower field with increasing x. A detailed comparison of experimental results with calculations based on a modified Pidgeon-Brown model allows us to estimate the $s\ensuremath{-}d$ and $p\ensuremath{-}d$ exchange-coupling constants, $\ensuremath{\alpha}$ and $\ensuremath{\beta},$ for this important III-V dilute magnetic semiconductor system.