Spin-Diffusion Lengths in Ag(4{\%}Sn) and Cu(2{\%}Ge) alloys*

Alloying Ag with a little Sn, or Cu with a little Ge, greatly increases elastic scattering of electrons---i.e., greatly decreases the electron mean-free-path (mfp), but does not produce much spin-flipping---i.e., leaves the electron spin-diffusion length, $l_{, }$relatively long. Thus, dilute AgSn and CuGe alloys were used to study effects of changing the mfp on current-perpendicular-to-plane (CPP) magnetoresistance [1] and current-induced magnetization switching (CIMS) [2], while leaving spin-flipping weak. Published transport data in dilute AgSn and CuGe alloys give only lower bounds for $l$ [3-5]. We find $l$ = 34 $\pm $ 4 nm for Ag(4{\%}Sn) and $l$ = 125 $\pm $ 10 nm for Cu(2{\%}Ge). [1] K. Eid et al., J. Magn. Magn. Mat. \textbf{224}, L205 (2001). [2] N. Theodoropoulou et al., Phys. Rev. B (rapid comm.) in press. [3] S.-F.Lee et al., J. Magn. Magn. Mat. \textbf{118}, L1 (993). [4] J. Bass et al, Mat. Sci. and Eng. \textbf{B31}, 77 (1995). [5] J. Bass and W.P. Pratt Jr., J. Phys. Cond. Matt. \textbf{19}, 183201 (2007).