Spin Diffusion Length in Ferromagnet/Superconductor Bilayers

We report a systematic study on the bilayers of ferromagnetic Sm
_1-x
Sr
_x
MnO
₃
(SSMO) and superconducting YBa
₂
Cu
₃
O
₇
(YBCO). The bilayer structure is composed of one SSMO layer of 10-nm thickness and one layer of YBCO of various thicknesses. The measurements of X-ray diffraction/reflectivity, resistivity, and magnetization were carried out for determining the crystalline properties and the superconducting temperatures of bilayers. A significant suppression of superconducting temperature is observed in all bilayers, indicating that the spin-polarized quasi-particles of SSMO are efficiently injected into the YBCO layer. The experimental results will be discussed in term of the spin diffusion length of polarized quasi-particles with a model of inverse proximity.