Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 28: Poster Session: Graphen; Transport properties; Transport in high magnetic fields / Quantum Hall effect; Metal-semiconductor hybrid systems

HL 28.16: Poster

Monday, March 11, 2013, 16:00–20:00, Poster A

Quasi-ballistic electron transport through bipolar localized magnetic fields — Tudor Chirila, Bernd Schüler, •Mihai Cerchez, and Thomas Heinzel — Heinrich Heine University Düsseldorf, Condensed Matter Laboratory, Universitätsstr. 1, 40225 Düsseldorf

We investigated the electron transport in hybrid ferromagnet/semiconductor devices produced by a series of two magnetic barriers of opposite polarity, placed on top of a Hall bar etched into a GaAs/AlGaAs heterostructure. The size of the Hall bar is comparable to the size of the magnetic structure and smaller than the mean free path of the electrons which places the structure in the quasi-ballistic regime [1]. The strength of the magnetic field profile is tuned by an external applied magnetic field, and the electron density is tuned by a metallic top gate. The magnetoresistance of the device shows non-ohmic behavior with characteristic transmission and reflection resonances. The measurements are in agreement with semi-classical simulations using the Landauer-Büttiker formalism with scattering [2, 3], and reveal the origin of the resonances residing in the quasi-ballistic transport of electrons confined by the edges of the Hall bar and the magnetic field profile.

[1] M. Cerchez and T. Heinzel, Appl. Phys. Lett., 98, 232111, 2011 [2] S. Hugger, M. Cerchez, H. Xu, and T. Heinzel, Phys. Rev B, 76, 195308, 2007 [3] M. Cerchez, S. Hugger, and T. Heinzel, Phys. Rev B, 75:035341, 2007