Regensburg 2000 – scientific programme

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HL: Halbleiterphysik

HL 40: Hauptvortrag

HL 40.1: Invited Talk

Friday, March 31, 2000, 09:30–10:30, H15

Hot-electron spin transport in semiconductor / ferromagnet heterostructures — •J.C. Lodder and R. Jansen — MESA+ Research Institute, University of Twente, P.O.box 217, 7500 AE Enschede, The Netherlands, phone +31 (53) 489 2750, fax +31 (53) 489 3343

The discovery of giant magnetoresistance in metallic multilayers has triggered a worldwide search for novel magnetotransport devices with prospective applications in magnetic sensors and memory elements. In this context, semiconductor / ferromagnet hybrid devices are attracting increasing attention. Here we present such a heterostructure, the spin-valve transistor, which combines functional properties of the ferromagnets and semiconductors. The spin-valve transistor relies on spin-transport of hot electrons, injected into a metallic spin valve with help of a Schottky barrier. A second Schottky barrier as the collector provides energy as well as momentum selection. This is shown to allow huge (> 200 %) magnetocurrent effects at room temperature in fields of only a few Oe. We discuss fabrication, operation and underlying physics of the device, emphasizing the role of the semiconductors as well as special features related to hot electrons, such as the ability to manipula! te the hot-electron energy and momentum with an external magnetic field, via spin-dependent scattering.