Reflection magnetic circular dichroism (MCD) spectrum was measured from 1.6 to 3.0eV to determine the nature of sp-d exchange in epitaxial InMnAs thin films. At room temperature and an applied field of 0.5 T, the MCD spectrum is composed of two types of transitions: a negative peak centered between 2.60 and 2.68 eV and a broad, negative response from 1.6 to 3.0 eV. For both transitions, ferromagnetic hysteresis and saturation are observed. The negative peak is attributed to the L-point critical transitions of InMnAs at 2.53 and 2.79 eV, respectively. The MCD enhancement at the L point is consistent with room temperature sp-d exchange splitting in metal organic vapor phase epitaxy grown InMnAs. The sp-d exchange is attributed to magnetic Mn dimers and trimers in the InMnAs. In contrast, the broad, featureless spectral response is consistent with spin dependent transitions between the Mn impurity band and conduction band.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)