Enhanced spin Hall torque efficiency in Pt100−xAlx and Pt100−xHfx alloys arising from the intrinsic spin Hall effect

We report that the spin Hall torque generated by Pt can be enhanced substantially by alloying with Al or Hf. We observe damping-like spin torque efficiency per unit applied current density as high as ξDLj=0.23±0.02, nearly twice the maximum value reported for pure Pt. To achieve this maximum efficiency, a very thin (0.5 nm) Pt spacer layer is inserted between the alloy and the ferromagnet being manipulated, to avoid a degraded spin transparency at the alloy/ferromagnet interface.

[1]  D. Hirashima,et al.  Giant orbital Hall effect in transition metals: origin of large spin and anomalous Hall effects. , 2008, Physical review letters.

[2]  Zhang,et al.  Spin hall effect in the presence of spin diffusion , 2000, Physical review letters.

[3]  Eiji Saitoh,et al.  Theory of spin Hall magnetoresistance , 2013, 1302.1352.

[4]  D. Ralph,et al.  Spin-torque ferromagnetic resonance induced by the spin Hall effect. , 2010, Physical review letters.

[5]  A. Hoffmann.  Spin Hall Effects in Metals , 2013, IEEE Transactions on Magnetics.

[6]  M. Naito,et al.  Intrinsic spin Hall effect and orbital Hall effect in 4 d and 5 d transition metals , 2007, 0711.1263.

[7]  Jianwang Cai,et al.  Large extrinsic spin Hall effect in Au-Cu alloys by extensive atomic disorder scattering , 2016 .

[8]  S. Parkin,et al.  Role of transparency of platinum–ferromagnet interfaces in determining the intrinsic magnitude of the spin Hall effect , 2015, 1504.07929.

[9]  M. Stiles,et al.  Current induced torques and interfacial spin-orbit coupling: Semiclassical modeling , 2013, 1301.4513.

[10]  R. J. Elliott,et al.  Theory of the Effect of Spin-Orbit Coupling on Magnetic Resonance in Some Semiconductors , 1954 .

[11]  Y. Yafet.  g Factors and Spin-Lattice Relaxation of Conduction Electrons , 1963 .

[12]  A. Fert,et al.  Extrinsic spin Hall effects measured with lateral spin valve structures , 2014, 1401.3445.

[13]  Robert A. Buhrman,et al.  Enhancement of the anti-damping spin torque efficacy of platinum by interface modification , 2015 .

[14]  H. Kontani,et al.  Indication of intrinsic spin Hall effect in 4d and 5d transition metals , 2010, 1008.0158.

[15]  Abhijit Ghosh,et al.  Interplay of spin-orbit torque and thermoelectric effects in ferromagnet/normal-metal bilayers , 2014, 1412.0865.

[16]  D. Ralph,et al.  Spin-Torque Switching with the Giant Spin Hall Effect of Tantalum , 2012, Science.

[17]  G. Guo,et al.  Intrinsic spin Hall effect in platinum: first-principles calculations. , 2008, Physical review letters.

[18]  D. Ralph,et al.  Dependence of the efficiency of spin Hall torque on the transparency of Pt/ferromagnetic layer interfaces , 2014, 1411.3379.

[19]  G. Vignale.  Ten Years of Spin Hall Effect , 2009 .

[20]  D. Ralph,et al.  Spin Torque Study of the Spin Hall Conductivity and Spin Diffusion Length in Platinum Thin Films with Varying Resistivity. , 2015, Physical review letters.

[21]  Michel Dyakonov,et al.  Current-induced spin orientation of electrons in semiconductors , 1971 .

[22]  A. Fert,et al.  Extrinsic spin Hall effect induced by iridium impurities in copper. , 2011, Physical review letters.

[23]  Jonathan Z. Sun,et al.  Spin Hall effect tunnelling spectroscopy , 2014, Nature Physics.

[24]  N. Reyren,et al.  Experimental evidences of a large extrinsic spin Hall effect in AuW alloy , 2014, 1403.7090.

[25]  J. Hirsch.  Spin Hall Effect , 1999, cond-mat/9906160.

[26]  Albert Fert,et al.  Spin Hall effect induced by resonant scattering on impurities in metals. , 2010, Physical review letters.

[27]  H. Ohno,et al.  Layer thickness dependence of the current-induced effective field vector in Ta|CoFeB|MgO. , 2012, Nature materials.

[28]  F. Casanova,et al.  Temperature dependence of spin diffusion length and spin Hall angle in Au and Pt , 2014, 1407.4770.

[29]  D. Ralph,et al.  Spin transfer torque devices utilizing the giant spin Hall effect of tungsten , 2012, 1208.1711.

[30]  A. Fert,et al.  Giant spin Hall effect induced by skew scattering from bismuth impurities inside thin film CuBi alloys. , 2012, Physical review letters.

[31]  N. Clark,et al.  Effect of microstructure on magnetic properties and anisotropy distributions in Co/Pd thin films and nanostructures , 2009 .