Epitaxial Growth of an n-type Ferromagnetic Semiconductor CdCr2Se4 on GaAs(001) and GaP(001)

We report the epitaxial growth of CdCr2Se4, an n-type ferromagnetic semiconductor, on both GaAs and GaP(001) substrates, and describe the structural, magnetic and electronic properties. Magnetometry data confirm ferromagnetic order with a Curie temperature of 130 K, as in the bulk material. The magnetization exhibits hysteretic behavior with significant remanence, and an in-plane easy axis with a coercive field of ~125 Oe. Temperature dependent transport data show that the films are semiconducting in character and n-type as grown, with room temperature carrier concentrations of n ~ 1 x 10^18 cm-3.Comment: 12 pages, 3 figure

Temperature dependent asymmetry of the nonlocal spin-injection resistance: evidence for spin non-conserving interface scattering

We report nonlocal spin injection and detection experiments on mesoscopic Co-Al2O3-Cu spin valves. We have observed a temperature dependent asymmetry in the nonlocal resistance between parallel and antiparallel configurations of the magnetic injector and detector. This strongly supports the existence of a nonequilibrium resistance that depends on the relative orientation of the detector magnetization and the nonequilibrium magnetization in the normal metal providing evidence for increasing interface spin scattering with temperature.Comment: 5 pages, 4 figures, accepted for publication in PRL, minor corrections (affiliation, acknowledgements, typo

The multiple reference principle component least mean squares algorithm: a projection based approach

The principal component least mean squares algorithm (PCLMS) is an elegant adaptive control algorithm for cancelling a tonal disturbance signal in active control applications, such as active noise control and active vibration isolation control. The algorithm removes the spatial correlation between the actuator inputs and the error sensor outputs to enable fast convergence of the adaptive controller. However, a drawback of the PCLMS algorithm is that it can only suppress a disturbance signal which contains a single frequency component. The contribution of this paper is that we present a numerically robust projection based approach in which the PCLMS is extended with the ability to suppress a disturbance signal which contains multiple frequency components. The potential of the algorithm is demonstrated by multi-tonal control on a realistic model of a real-time vibration isolation set-up. The algorithm is shown to outperform the traditional filtered-x least mean squares algorithm