Spin Torque Study of the Spin Hall Conductivity and Spin Diffusion Length in Platinum Thin Films with Varying Resistivity

Abstract

We report measurements of the spin torque efficiencies in perpendicularly-magnetized Pt/Co bilayers where the Pt resistivity Pt ρ is strongly dependent on thickness Pt t . The damping-like spin Hall torque efficiency per unit current density, DL j ξ , varies significantly with Pt t , exhibiting

Spin-Swapping Transport and Torques in Ultrathin Magnetic Bilayers

“…Nonetheless, recent experiments suggest that the inverse spin galvanic effect might not be the sole origin of fieldlike torque in ultrathin magnetic bilayers. Indeed, (i) sizable fieldlike torques have been reported in systems where interfacial spin-orbit coupling is expected to be small [22], and (ii) significant modulation of the fieldlike torque has been obtained upon varying the heavy metal thickness [22][23][24]. While both observations contradict the inverse spin galvanic effect scenario, no alternative mechanism has been identified, despite intense theoretical efforts [21,25,26].…”

“…In fact, most of these experiments are conducted on multilayers with thicknesses from 10 nm down to less than 1 nm [22][23][24]34]. In sputtered thin films the grain size ranges from 5 to 10 nm, which implies that the transport is not diffusive and that extrinsic spin swapping can lead to sizable fieldlike torque, even in the absence of interfacial inverse spin galvanic effect.…”

Continuous Tuning of the Magnitude and Direction of Spin‐Orbit Torque Using Bilayer Heavy Metals

“…In addition, the resistivity Pt  of the Pt layer is found to increase dramatically with decreasing the Pt thickness (see Supporting Information Figure S5), which is a well-known phenomenon due to strong diffusive scattering at the Pt surface. [41] The relative current density and current distribution in metallic layers can be obtained (see Table S1 and S2). The ratio of distributed currents in Pt to that in Ta increases dramatically with increasing the Pt thickness (see Supporting Information Table S2, Column 5).…”

Temperature dependence of spin-orbit torques across the magnetic compensation point in a ferrimagnetic TbCo alloy film

“…SOTs have been identified and quantified by a variety of techniques including spin-torque ferromagnetic resonance [2,7,14,17,19,25], quasistatic magnetization tilting probed through harmonic voltage measurements [6,[8][9][10][11][12][13]17,[19][20][21][22][23][24][25][26]28,31], and current-induced hysteresis loop shift measurements [18,32,33]. Most studies of SOTs have focused on ultrathin metallic ferromagnet/heavy-metal bilayers with interfacial perpendicular magnetic anisotropy (PMA) [1][2][3][5][6][7][8][9][11][12][13][15][16][17][18][19][20][21][22][23][24][25]…”

“…SOTs with both a fieldlike and dampinglike character can manifest in such systems, with the latter capable of driving magnetization switching [1][2][3][4][5]7,9,[11][12][13]15,21,22,24] and magnetic domain wall motion [26][27][28][29][30][31]. SOTs have been identified and quantified by a variety of techniques including spin-torque ferromagnetic resonance [2,7,14,17,19,25], quasistatic magnetization tilting probed through harmonic voltage measurements [6,[8][9][10][11][12][13]17,[19][20][21][22][23][24][25][26]28,31], and current-induced hysteresis loop shift measurements [18,32,33]. Most studies of SOTs have focused on ultrathin metallic ferromagnet/heavy-metal bilayers with interfacial perpendicular magnetic ani...…”