Spin diffusion length and polarization of ferromagnetic metals measured by spin-absorption technique in lateral spin valves

G. Zahnd (1) , Laurent Vila (1) , V. Pham (1) , M Cosset-Cheneau (1) , W Lim (1) , A Brenac (1) , P Laczkowski (1) , A Marty (1) , J P Attané (1)

1 SPINTEC - SPINtronique et TEchnologie des Composants

We present measurements of pure spin current absorption on lateral spin valves. By varying the width of the absorber we demonstrate that spin current absorption measurements enable to characterize efficiently the spin transport properties of ferromagnetic elements. The analytical model used to describe the measurement takes into account the polarization of the absorber. The analysis of the measurements allows thus determining the polarization and the spin diffusion length of a studied material independently, contrarily to most experiments based on lateral spin valves where those values are entangled. We report the spin transport parameters of some of the most important materials used in spinorbitronics (Co60Fe40, Ni81Fe19, Co, Pt, and Ta), at room and low (10 K) temperatures. TEXT Recent advances in spinorbitronics have evidenced the need for new characterization techniques, measuring precisely the spin-dependent material properties. Indeed, parameters such as the damping, the polarization, the spin diffusion length, the Dzyaloshinskii-Moriya interaction (DMI) or the spin Hall angle are key factors to understand and control various mechanisms: spin transfer torque 1,2,3 , spin texture dues to DMI 4,5,6 , or charge-to-spin conversion based on spin orbit coupling effects at Rashba interfaces 7,8 , in the bulk of SHE materials 9,10 , or in topological insulators 11. Among those basic material parameters, the spin diffusion length occupies a primordial role in all spin transport mechanisms. Pioneer spin transport measurements of the spin diffusion length 12,13,14 have been performed on vertical structures, using thickness dependences, but the data available on such material parameters determination are often restricted to low temperatures. Almost two decades later, the determination of short spin diffusion lengths remains difficult, for instance in ferromagnetic alloys and heavy metals. The need for precise measurement techniques has however become crucial, in particular in spinorbitronics: the * [e-mail] †

Domaines: Science des matériaux [cond-mat.mtrl-sci]

G. Zahnd, Laurent Vila, V. Pham, M Cosset-Cheneau, W Lim, et al.. Spin diffusion length and polarization of ferromagnetic metals measured by spin-absorption technique in lateral spin valves. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2018, 98 (17), ⟨10.1103/PhysRevB.98.174414⟩. ⟨hal-01908888⟩