Large magnetoresistance in a ferromagnetic Zener diode

¹ Electron Physics Laboratory, Department of Electrical and Communications Engineering, Helsinki University of Technology P.O. Box 3500, FIN-02015 HUT, Finland
² VTT Information Technology, Microelectronics Centre P.O. Box 1208, FIN 02044 VTT, Finland
³ Pulsed Field Group, Laboratory of Solid State Physics and Magnetism K. U. Leuven - Celestijnenlaan 200D, 3001 Leuven, Belgium

Received: 25 April 2005
Accepted: 28 June 2005

Abstract

We investigate spin-dependent interband tunnelling in a ferromagnetic  Zener diode. The ferromagnetic pn-junction is fabricated with a -doped p-type layer on top of a nonmagnetic n-type substrate. When both sides of the junction are heavily doped, a large magnetic-field–dependent tunnelling effect can be seen at low temperatures in the measured current-voltage (I-V) characteristics. A model for the tunneling current in a ferromagnetic Zener diode is presented, and the observed effects are explained by the exchange interaction related splitting of the valence band states in . To our knowledge, this is the first time the effect of the band splitting and a large magnetoresistance related to the tunnelling processes have been observed experimentally in the I-V characteristics of a ferromagnetic Zener diode.