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 In$_{1-x}$Mn$_x$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 {\em s-d} and {\em p-d} exchange coupling constants, $\alpha$ and $\beta$, for this important III-V dilute magnetic semiconductor system. 
M. A. Zudov, J. Kono, Y. H. Matsuda, T. Ikaida, N. Miura, H. Munekata,   G. D. Sanders, Y. Sun, and C. J. Stanton