Assembling ferromagnetic single-electron transistors by atomic force microscopy

Abstract

We demonstrate the assembly of nanoscale ferromagnetic single-electron transistors usingatomic force microscopy for imaging as well as for nanoscale manipulation. A single 30 nmAu disc, forming the central island of the transistor, is manipulated with angstromprecision into the gap between a plasma-oxidized Ni source and drain electrodes. Thetunnel resistances can be tuned in real time during the device fabrication by repositioningthe Au disc. Transport measurements reveal long-term stable single-electron transistorcharacteristics at 4.2 K. The well-controlled devices with very small central islands facilitatefuture in-depth studies of the interplay between Coulomb blockade, spin-dependenttunnelling and spin accumulation in ferromagnetic single-electron transistors at elevatedtemperatures.