| Spintronics is an emerging technology that exploits the spin degree of freedom of the electron as well as its charge. One of the barriers that must be overcome in order to develop this technology is the creation of a spin-polarized current inside a semiconductor at room temperature. One approach to achieving this is the formation of direct spin injection contacts. Here, interfaces between ferromagnetic materials and semiconductors are required. Fe layers grown on GaAs has been the focus of much work in recent years since high quality epitaxial Fe layers can be easily grown on GaAs, and spin-injection has been demonstrated for this system. However, the limited spin-injection efficiency achieved to date requires much improvement in order to be suitable for device applications. This work focuses on obtaining a better understanding of the interface between epitaxial layers of Fe and GaAs, on overlayer effects on the magnetic properties of buried Fe layers, and on the effects that thermal processing has on the interface. During this investigation I observed several unexpected phenomena, including simultaneous spin-wave modes that developed in annealed Fe layers, a critical annealing temperature where the system undergoes both structural and magnetic phase transitions, and overlayer material effects on the magnetization and anisotropy of the Fe layer. The magnetic properties were primarily studied using ultra-sensitive Brillouin light scattering (BLS). A fitting program was developed in this study to extract physical constants from BLS data. |
