Studies of impurities in magnetic semiconductors: an example of important XAFS applications

The x-ray absorption fine structure (XAFS) technique has been employed to i nvestigate the local structure and valency about Mn and Fe ions in the III- V diluted magnetic semiconductors In1-xMnxAs and Ga1-xFexAs, prepared by mo lecular-beam-epitaxy under various growth conditions. These new systems are promising magnetic materials of considerable current interest and with imp ortant technical applications including photo-carrier induced magnetism and spin-polarized current devices. The local structure around the magnetic io ns can play a pivotal role in affecting the magnetic properties of these se miconductors. Local structure information obtained from XAFS has provided t he first direct evidence that the magnetic impurities can indeed substitute for the cation host atoms in samples prepared under appropriate conditions .