Interface specific-resistance and scattering asymmetry of permalloy/Al

Stimulated by observations by Garcia [Bull. Am. Phys. Soc. 50, 237 (2005)] of much smaller magnetoresistances (MR) for PyAlPy nanopillars than for PyCuPy, but only slightly larger switching currents Is for current-induced magnetization switching (CIMS), we have determined the specific resistance, (area A times resistance R), 2 AR PyAl*, and the scattering asymmetry, γPyAl, at 4.2 K for interfaces between sputtered permalloy (Py) and aluminum (Al): 2 AR PyAl* =8.5±1 fΩ m2 is an order of magnitude larger than the standard value of 2 AR PyCu* =1.0±0.1 fΩ m2, and γPyAl = 0.025 -0.01 +0.045 is an order of magnitude smaller than γPyCu =0.7±0.1. These two differences qualitatively account for the smaller MR but comparable Is with Al.