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arXiv · 0908.4375

Measurement of spin memory lengths in PdNi and PdFe ferromagnetic alloys

H. Arham·T. S. Khaire·R. Loloee·W. P. Pratt, Jr.·Norman O. Birge
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Abstract

Weakly ferromagnetic alloys are being used by several groups in the study of superconducting/ferromagnetic hybrid systems. Because spin-flip and spin-orbit scattering in such alloys disrupt the penetration of pair correlations into the ferromagnetic material, it is desirable to have a direct measurement of the spin memory length in such alloys. We have measured the spin memory length at 4.2 K in sputtered Pd0.88Ni0.12 and Pd0.987Fe0.013 alloys using methods based on current-perpendicular-to-plane giant magnetoresistance. The alloys are incorporated into hybrid spin valves of various types, and the spin memory length is determined by fits of the Valet-Fert spin-transport equations to data of magnetoresistance vs. alloy thickness. For the case of PdNi alloy, the resulting values of the spin memory length are lsf(PdNi) = 2.8 +/- 0.5 nm and 5.4 +/- 0.6 nm, depending on whether or not the PdNi is exchange biased by an adjacent Permalloy layer. For PdFe, the spin memory length is somewhat longer, lsf(PdFe) = 9.6 +/- 2 nm, consistent with earlier measurements indicating lower spin-orbit scattering in that material. Unfortunately, even the longer spin memory length in PdFe may not be long enough to facilitate observation of spin-triplet superconducting correlations predicted to occur in superconducting/ferromagnetic hybrid systems in the presence of magnetic inhomogeneity.

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H. Arham, T. S. Khaire, R. Loloee, W. P. Pratt, Jr., Norman O. Birge. 2009-08-30. Measurement of spin memory lengths in PdNi and PdFe ferromagnetic alloys. https://doi.org/10.1103/physrevb.80.174515

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