Magnetic moment in diluted magnetic semiconductor GaGdAs measured by HX-MCD

In order to elucidate the relationship between magnetism and electron states, we fabricate diluted magnetic semiconductor superlattice(SL) GaGdAs/GaAs and monolayer(ML) GaGdAs by MBE, and analyze electronic states by XAS(x-ray absorption spectrum) and MCD(magnetic circular dichroism), comparing to macroscopic magnetization. Samples with various Gd compositions were grown on GaAs (001) substrate, changing Gd cell temperature as 1300-1450 °C. We made GaGdAs/GaAs SL and ML samples by controlling shutter sequence of Gd K-cell. In MCD spectra at Gd L2-edge, where the MCD signals were normalized by edge jumps of XAS, the magnitude of MCD signal is supposed to reflect the magnetization of Gd ion. Comparing the MCD magnitudes to macroscopic magnetization, it is found that the Gd magnetic moment in GaGdAs can be decided by not only Gd concentration but also the other growth condition, such as substrate temperature or grown rate of matrix GaAs.