Spin-to-charge conversion using Rashba coupling at the interface between non-magnetic materials

The Rashba effect is an interaction between the spin and the momentum of electrons induced by the spin-orbit coupling (SOC) in surface or interface states. Its potential for conversion between charge and spin currents has been theoretically predicted but never clearly demonstrated for surfaces or interfaces of metals. Here we present experiments evidencing a large spin-charge conversion by the Bi/Ag Rashba interface. We use spin pumping to inject a spin current from a NiFe layer into a Bi/Ag bilayer and we detect the resulting charge current. As the charge signal is much smaller (negligible) with only Bi (only Ag), the spin-to-charge conversion can be unambiguously ascribed to the Rashba coupling at the Bi/Ag interface. This result demonstrates that the Rashba effect at interfaces can be used for efficient charge-spin conversion in spintronics.

[1]  S. Maekawa,et al.  Inverse spin-Hall effect induced by spin pumping in metallic system , 2011 .

[2]  S. Bandiera,et al.  Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection , 2011, Nature.

[3]  G. Vignale,et al.  Spin‐orbit interaction in a two‐dimensional electron gas: A SU(2) formulation , 2011, 1110.5279.

[4]  I. Miron,et al.  Current-induced spin–orbit torques , 2011, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[5]  P. Hofmann,et al.  Hole dynamics in a two-dimensional spin-orbit coupled electron system: Theoretical and experimental study of the Au(111) surface state , 2009 .

[6]  Aurelien Manchon,et al.  Nonequilibrium intrinsic spin torque in a single nanomagnet , 2008 .

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

[8]  Eiji Saitoh,et al.  Conversion of spin current into charge current at room temperature: Inverse spin-Hall effect , 2006 .

[9]  A. Brataas,et al.  Enhanced gilbert damping in thin ferromagnetic films. , 2001, Physical review letters.

[10]  A. Taleb-Ibrahimi,et al.  Giant anisotropy of spin-orbit splitting at the bismuth surface. , 2012, Physical review letters.

[11]  M. Ibarra,et al.  Role of the surface states in the magnetotransport properties of ultrathin bismuth films , 2010 .

[12]  D. Apalkov,et al.  Matching domain-wall configuration and spin-orbit torques for efficient domain-wall motion , 2012, 1210.3049.

[13]  Sadamichi Maekawa,et al.  Concepts in spin electronics , 2006 .

[14]  D. D. Awschalom,et al.  Observation of the Spin Hall Effect in Semiconductors , 2004, Science.

[15]  M. Tinkham,et al.  Direct electronic measurement of the spin Hall effect , 2006, Nature.

[16]  H. Nakayama,et al.  Interface induced inverse spin Hall effect in bismuth/permalloy bilayer , 2012 .

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

[18]  J. E. Pearson,et al.  Detection and quantification of inverse spin Hall effect from spin pumping in permalloy/normal metal bilayers , 2010, 1009.5089.

[19]  V. M. Edelstein.  Spin polarization of conduction electrons induced by electric current in two-dimensional asymmetric electron systems , 1990 .

[20]  K. Kern,et al.  Giant spin splitting through surface alloying. , 2007, Physical review letters.

[21]  Bernard Rodmacq,et al.  Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer. , 2010, Nature materials.

[22]  B. V. van Wees,et al.  Spin caloritronics. , 2011, Nature materials.

[23]  E. Rashba,et al.  Properties of a 2D electron gas with lifted spectral degeneracy , 1984 .

[24]  S. Maekawa,et al.  Giant enhancement of spin accumulation and long-distance spin precession in metallic lateral spin valves. , 2011, Nature materials.

[25]  M. Ibarra,et al.  Structural and magnetotransport properties of Bi thin films grown by thermal evaporation , 2010 .

[26]  Xiaofeng Jin,et al.  Bi(111) thin film with insulating interior but metallic surfaces. , 2012, Physical review letters.