Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 37: Quantenpunkte und -drähte: Transporteigenschaften

HL 37.1: Vortrag

Donnerstag, 11. März 2004, 10:15–10:30, H13

Spin Blockade in Capacitively Coupled Quantum Dots — •M. C. Rogge, C. Fühner, U. F. Keyser, and R. J. Haug — Institut für Festkörperphysik, Universität Hannover, D-30167 Hannover

We present transport measurements on a lateral double dot produced by combining local anodic oxidation and electron beam lithography [1]. Our device is based on a GaAs/AlGaAs heterostructure containing a two-dimensional electron system (2DES) 34 nm below the surface. We use an atomic force microscope (AFM) to write the basic double dot structure by local anodic oxidation (LAO) [2]. We complete our device with a metallic top gate patterned with e-beam lithography to add the function of controlled tunability of the interdot coupling. We investigate our device in transport measurements in a 3He/4He dilution refrigerator and demonstrate, that we can switch between capacitive and tunnel coupling with top gate voltage. In the regime of capacitive coupling we focus on the magnetic field dependence in the Coulomb blockade regime. We observe oscillating peak positions and peak amplitudes for transport over one dot. This is explained by the phenomenon of spin blockade [3], which has not been observed in LAO-devices so far. We investigate this effect and analyze the influence of capacitive interdot coupling in this regime [4].

[1] M. C. Rogge et al., Appl. Phys. Lett. 83, 1163 (2003)

[2] U. F. Keyser et al., Appl. Phys. Lett. 76, 457 (2000)

[3] M. Ciorga et al., Phys. Rev. B 61, R16315 (2000)

[4] M. C. Rogge et al., cond-mat/0310469 (2003)