Title :
Evidence for modification of the superconducting order parameter in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films by injection of a spin polarized current
Author :
Chrisey, D.B. ; Osofsky, M.S. ; Horwitz, J.S. ; Soulen, R.J. ; Woodfield, B. ; Byers, J. ; Daly, G.M. ; Dorsey, P.C. ; Pond, J.M. ; Johnson, M. ; Auyeung, R.C.Y.
Author_Institution :
Naval Res. Lab., Washington, DC, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
We have deposited novel bilayer thin films of a ferromagnetic material and YBa/sub 2/Cu/sub 3/O/sub 7/ separated by a thin Au diffusion barrier to study the effects of a spin polarized nonequilibrium quasiparticle population on the superconducting order parameter. Thin films of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta//, Au, and Permalloy (Ni/sub 0.8/Fe/sub 0.2/) were deposited by pulsed laser deposition onto (100) MgO, SrTiO/sub 3/, or LaAlO/sub 3/ substrates. A thin stripe of YBa/sub 2/Cu/sub 3/,O/sub 7-/spl delta//, was patterned and two pairs of Au cross stripes for current and voltage contact were deposited at each end. Between these contacts a Permalloy and a Au cross stripe was also deposited to serve as the spin polarized and unpolarized quasiparticle injection sources, respectively. Utilizing this pseudo-three terminal device configuration we have in some samples measured reductions in the superconducting order parameter at the ferromagnet contact as compared to the normal metal contact. Details of this experiment, issues for optimized fabrication, and theoretical issues are discussed.
Keywords :
barium compounds; critical currents; diffusion barriers; electron spin polarisation; ferromagnetism; high-temperature superconductors; pulsed laser deposition; quasiparticles; superconducting junction devices; superconducting thin films; yttrium compounds; (100) MgO substrate; Au; Au cross stripes; LaAlO/sub 3/; LaAlO/sub 3/ substrate; MgO; Ni/sub 0.8/Fe/sub 0.2/; Permalloy; SrTiO/sub 3/; SrTiO/sub 3/ substrate; YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// films; YBa/sub 2/Cu/sub 3/O/sub 7/; bilayer thin films; current contact; ferromagnet contact; ferromagnetic material; normal metal contact; optimized fabrication; pseudo-three terminal device configuration; pulsed laser deposition; spin polarized current injection; spin polarized nonequilibrium quasiparticle population; superconducting order parameter; superconducting transistors; thin Au diffusion barrier; thin stripe; unpolarized quasiparticle injection sources; voltage contact; Gold; Iron; Magnetic materials; Optical pulses; Polarization; Pulsed laser deposition; Sputtering; Superconducting materials; Superconducting thin films; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
