Search

Abstract: We present a theoretical study on spin-dependent transport of electrons in any anti-parallel double -magnetic-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe on the surface of a semiconductor heterostructure. A general fomula of tranmission probability for electrons tunneling through this kind of nanostructures, is obtained. It is shown that large spin-polarized current can be achieved in such a device. It also is shown that the degree of electron-spin polarization is strongly dependent upon magnetic-strength difference of two -barriers. These interesting properties may provide an alternative scheme to spin-polarize electrons into semiconductors, and this device may be used as a tunable spin-filter. [Copyright &y& Elsevier]

Abstract: We measured temperature dependence of a spin polarization of field-emitted electrons from a single-crystalline magnetite (Fe3O4) whisker with 〈110〉 orientation. The spin polarization of emitted electrons began to increase above 130K corresponding to the temperature of Verwey point (T v ). The increase is considered as reflection of the change of the spin state near the Fermi level due to the Verwey transition. Our experimental results support a localization of t2g orbital electrons below the Verwey point and a model of charge ordering for magnetite. [Copyright &y& Elsevier]