Europhys. Lett.
Volume 71, Number 5, September 2005
Page(s) 811 - 816
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 27 July 2005
Europhys. Lett., 71 (5), pp. 811-816 (2005)
DOI: 10.1209/epl/i2005-10142-y

Large magnetoresistance in a ferromagnetic $\chem{GaMnAs/GaAs}$ Zener diode

H. Holmberg1, N. Lebedeva1, S. Novikov1, J. Ikonen1, P. Kuivalainen1, 2, M. Malfait3 and V. V. Moshchalkov3

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
published online 27 July 2005

We investigate spin-dependent interband tunnelling in a ferromagnetic $\chem{(Ga,Mn)As/}$ $\chem{GaAs}$ Zener diode. The ferromagnetic pn-junction is fabricated with a $\chem{Mn}$-doped p-type $\chem{GaAs}$ layer on top of a nonmagnetic n-type $\chem{GaAs}$ 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 $\chem{(Ga,Mn)As}$. 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.

73.61.Ey - III-V semiconductors.
75.50.Pp - Magnetic semiconductors.
85.75.-d - Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields.

© EDP Sciences 2005