Tunneling magnetoresistance effect in a few-electron quantum-dot spin valve

Abstract

We demonstrate the tunneling magnetoresistance (TMR) effect through a semiconductor quantum dot (QD) with a few electrons in a lateral QD spin-valve device. At one-to-two electron transition, only inverse TMR effect is observed, where the TMR ratio is relatively large compared with the value based on the Julliere model. When the bias window reaches near the charging energy of the QD, the inverse TMR almost disappears. These features can be interpreted in terms of spin transport via the ground state of a two-electron QD.