AVS 49th International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI-TuP

Paper MI-TuP1
Enhanced Magnetoresistance in Ferromagnetic Vertical Single Electron Transistor

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Aspects of Magnetism
Presenter: S. Haraichi, National Institute of Advanced Industrial Science and Technology, Japan
Authors: S. Haraichi, National Institute of Advanced Industrial Science and Technology, Japan
T. Wada, National Institute of Advanced Industrial Science and Technology, Japan
Correspondent: Click to Email
Recently, such novel phenomena as enhancement of magnetoresistance and magneto-Coulomb oscillation have been found in ferromagnetic single electron transistors (SET). However, because the areas of the ferromagnetic-insulator- ferromagnetic (FIF) tunnel junctions were as large as 0.02 ???, extremely low temperature as 20 mK was required to obtain Coulomb blockade and spin-dependent tunneling transport simultaneously. In order to elucidate the mechanism of those phenomena at relatively high temperatures and to realize such novel devices as spin-memories and spin-transistors, FIF tunnel junctions with 10 nm sizes are necessary. We have developed Si based inorganic electron beam resist process suitable for integration by which 10 nm resolution can be achieved. Using this process, nanometer-scale vertical FIF tunnel junctions are fabricated with high reliability. In this paper, we will report a fabrication process for ultra-small ferromagnetic vertical SET by modifying the above inorganic resist process, and the electrical characteristics especially spin-dependent tunneling transport of fabricated devices. The enhanced magnetoresistance changes over several times in the Coulomb blockade (CB) region in magnetic fields of around 100 mT at 14 K, while that changes only several % in the outside of the CB region. This strong enhancement is explained by the higher-order tunneling process.