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We present transport measurements on a lateral double dot produced by combining local anodic oxidation and electron beam lithography. We investigate the tunability of our device and demonstrate that we can switch on and off tunnel coupling between both dots in addition to capacitive coupling. In the regime of pure capacitive coupling, we observe the phenomenon of spin blockade in a magnetic field and analyze the influence of capacitive interdot coupling on this effect. [ABSTRACT FROM AUTHOR]

We have combined direct nanofabrication by local anodic oxidation with conventional electron-beam lithography to produce a parallel double quantum dot based on a GaAs/AlGaAs heterostructure. The combination of both nanolithography methods allows fabrication of robust in-plane gates and Cr/Au top-gate electrodes on the same device for optimal controllability. This is illustrated by the tunability of the interdot coupling in our device. We describe our fabrication and alignment scheme in detail and demonstrate the tunability in low-temperature transport measurements. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]