Spin degree of freedom is traditionally neglected in semiconductor devices and often spin is accouned for by a factor of 2 in the density of states. It is primarily due to weak coupling of spins to the environment, which makes their detection and manipulation a formidable task. However, this very property makes spins attractive for such applications as quantum information processing or memory devices, where long retention times are important. I will start by briefly describing current research in my lab, which is focused on isolation, manipulation and detection of spins at different density scales, and on understanding relevant interactions and relaxation mechanisms. With a single-spin we are aiming to design a qubit where information will be encoded in spin orientation. On a multiple-spin level we are working on efficient spin injection and detection of polarized currents in non-magnetic semiconductors. At yet higher spin densities we are working to understand the nature of ferromagnetism in dilute magnetic semiconductors and to find ways to manipulate orientation of magnetic domains electrostatically.

In the main part I will talk about spin-polarized currents and how we create and detect them. We show that in a non-magnetic semiconductor with spin-orbit interactions spins can be spatially separated in a “spin spectrometer”, utilizing difference in momenta and, thus, cyclotron radii, for two spin polarizations. For holes in GaAs almost 100% bipolar spin filtering has been achieved in magnetic focusing geometry with spatial separation of polarized beams by 0.2 microns. The new technique of spin injection/detection opens a possibility to investigate density and electric field dependence of spin-orbit interactions, and spin dynamics in a "time of flight" experiments. We used this new technique to demonstrate spontaneous spin polarization in low density one-dimensional wires.

After the talk everyone is welcome for a slide-show demonstration of my personal quest toward the magnetic North Pole, which culminated this summer in the summit of Mt. McKinnley (6194m or 20320ft) in Alaska, the highest peak above the Arctic Circle.