* Speaker: Prof. Sadamichi Maekawa(Institute for Materials Research, Tohoku University)

* Date & Time: Nov. 9 (Mon) 11:00 / 14:00

* Place: #512, Hogil Kim Memorial Bldg., POSTECH

* Abstract

Spin-dependent transport in nanostructures is of great interest not only in the emergence of new phenomena but also in the potential applications to spin electronic devices and information technologies [1]. Recent experimental and theoretical studies have demonstrated that the spin-polarized carriers injected from a ferromagnet (F) into a nonmagnetic material (N) such as normal conducting metal, semiconductor and superconductor, create nonequilibrium spin accumulation and spin current over the spin diffusion length. Efficient spin injection, spin accumulation, spin transfer and spin detection are key factors for utilizing the spin degree of freedom as a new functionality in spin electronic devices.

Here, we examine the nonlocal spin transport in a nanostructure device consisting of ferromagnetic injector (F1) and detector (F2) electrodes connected to a normal conductor (N) or a superconductor (SC). We explore how the spin transport in such a device depends on the nature of interface (metallic-contact or tunnel junction) and materials parameters of electrodes by solving the spin-dependent transport equations, and obtain the conditions for efficient spin injection, spin accumulation, and spin current in the device. In a device containing a superconductor (F1/SC/F2), the effect of superconductivity on the spin transport is investigated. The spin Hall effect in nonmagnetic metals and superconductors is discussed.

This work has been done in collaboration with S. Takahashi.

[1] Concepts in Spin-Electronics, ed. S. Maekawa

(Oxford University Press, UK, 2006).