Type of Document	Dissertation
Author	Anaya, Armando A.
Author's Email Address	aanaya00@yahoo.com, gt4769a@mail.gatech.edu
URN	etd-03162005-175619
Title	Spin Valve Effect in Ferromagnet-Superconductor-Ferromagnet Single Electron Transistor
Degree	Doctor of Philosophy
Department	Physics
Advisory Committee	Advisor Name Title Davidovic, Dragomir Committee Member De Heer, Walter Committee Member Ferguson, Ian Committee Member First, Phillip Committee Member Sa De Melo, Carlos Committee Member
Keywords	magnetoresistance nanotechnology single electron transitor spintronics
Date of Defense	2005-01-28
Availability	unrestricted
Abstract This thesis describes a research of suppression of superconducting gap in a superconducting island of a Ferromagnetic-Superconducting-Ferromagnetic Single-Electron-Transistor due to the fringing magnetic fields produced by the ferromagnetic leads. The devices are working below the critical temperature of the superconducting gap. A model is proposed to explain how the fringing magnetic field produced by the leads is strong enough to suppress the superconducting gap. The peak of the fringing magnetic field produced by one lead reaches 5000 oe. It is observed an inverse tunneling magneto resistance during the suppression of the superconducting gap, obtaining a maximum absolute value 500 times greater than the TMR in the normal state where the efficiency of the spin injection is low. It is concluded that the suppression of the superconducting gap is due to fringing magnetic field and not to the spin accumulation because the low efficiency of the spin injection. It is suggested a new geometry to reduce the effect of the fringing magnetic field so it can be obtained a suppression of the superconductivity due to the spin accumulation. It is described the qualitatively behavior of the IV characteristic when the suppression of the superconductivity is due to spin accumulation.
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