We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs/GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wave vector range from zero to 6x10(4) cm-1. We find that the spin polarization lifetime is maximal at a nonzero wave vector, in contrast with expect...

We create and study persistent currents in a toroidal two-component Bose gas, consisting of 87Rb atoms in two different spin states. For a large spin-population imbalance we observe supercurrents persisting for over two minutes. However, we find that the supercurrent is unstable for spin polarization below a well-defined critical value. We also investigate the role of phase coherence between th...

A study has been made of the mechanisms of dynamic polarization of nuclei in organic materials at temperatures below 1 K and in magnetic fields up to 50 kG. After a summary of the mechanisms of dynamic polarization, the experimental results on 1,2-propanediol, doped with paramagnetic Crv complexes, are compared quantitatively with a spin temperature model of Borghini, in which it is assumed tha...

Spin Hall effects are a collection of phenomena, resulting from spin-orbit coupling, in which an electrical current flowing through a sample can lead to spin transport in a perpendicular direction and spin accumulation at lateral boundaries. These effects, which do not require an applied magnetic field, can originate in a variety of intrinsic and extrinsic spin-orbit coupling mechanisms and dep...

Spin Hall effects are a collection of phenomena, resulting from spin-orbit coupling, in which an electrical current flowing through a sample can lead to spin transport in a perpendicular direction and spin accumulation at lateral boundaries. These effects, which do not require an applied magnetic field, can originate in a variety of intrinsic and extrinsic spin-orbit coupling mechanisms and dep...

Title of dissertation: SPIN INJECTION AND DETECTION IN COPPER SPIN VALVE STRUCTURES Samir Garzón, Doctor of Philosophy, 2005 Dissertation directed by: Richard A. Webb Department of Physics We report measurements of spin injection and detection in a mesoscopic copper wire from which the electron spin relaxation time and the spin current polarization in copper can be found. Spin injection is real...

We experimentally demonstrate the control of the light polarization emitted by a 1310 nm dilute nitride spin-Vertical Cavity Surface Emitting Laser (VCSEL) at room temperature. This is achieved by means of a combination of polarized optical pumping and polarized optical injection. Without external injection the polarization of the optical pump controls that of the spin-VCSEL. However, the addit...

Some full-Heusler alloys, such as Co(2)MnSi and Co(2)MnGe, are expected to be half-metallic ferromagnetic material, which has complete spin polarization. They are the most promising materials for realizing half-metallicity at room temperature owing to their high Curie temperature. We demonstrate a huge tunnel magnetoresistance effect in a magnetic tunnel junction using a Co(2)MnSi Heusler alloy...

Dynamic nuclear polarization (DNP) is an attractive method for initializing nuclear spins that are strongly coupled to optically active electron spins because it functions at room temperature and does not require strong magnetic fields. In this Letter, we theoretically demonstrate that DNP, with near-unity polarization efficiency, can be generally realized in weakly coupled electron spin-nuclea...

We present a detailed DFT-based electronic structure calculation of Co1–xFexS2, a model ferromagnetic system with tunable spin polarization, P. It is shown that the position of the Fermi level and the spin polarization can be controlled by x, the Fe concentration. We predict that for x = 0 the system has predominantly minority carriers corresponding to P = –75%. Upon doping to x = 0.25, the sys...