Control of Terahertz Emission by Ultrafast Spin-Charge Current Conversion at Rashba Interfaces.

We show that a femtosecond spin-current pulse can generate terahertz (THz) transients at Rashba interfaces between two nonmagnetic materials. Our results unambiguously demonstrate the importance of the interface in this conversion process that we interpret in terms of the inverse Rashba Edelstein effect, in contrast to the THz emission in the bulk conversion process via the inverse spin-Hall effect. Furthermore, we show that at Rashba interfaces the THz-field amplitude can be controlled by the helicity of the light. The optical generation of electric photocurrents by these interfacial effects in the femtosecond regime will open up new opportunities in ultrafast spintronics.

[1]  A. Hoffmann,et al.  New pathways towards efficient metallic spin Hall spintronics , 2015, 1511.07739.

[2]  Ronger Zheng,et al.  Powerful and Tunable THz Emitters Based on the Fe/Pt Magnetic Heterostructure , 2016, 1607.02814.

[3]  Wei Zhang,et al.  Interface-driven spin-torque ferromagnetic resonance by Rashba coupling at the interface between nonmagnetic materials , 2015, 1508.01410.

[4]  Y. Fainman,et al.  All-optical control of ferromagnetic thin films and nanostructures , 2014, Science.

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

[6]  A. Fert,et al.  Conversion between spin and charge currents with topological insulators , 2016 .

[7]  J. Pearson,et al.  Spin pumping and inverse Rashba-Edelstein effect in NiFe/Ag/Bi and NiFe/Ag/Sb , 2015 .

[8]  J. Walowski,et al.  Perspective: Ultrafast magnetism and THz spintronics , 2016 .

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

[10]  R. Winkler,et al.  Generation of spin currents and spin densities in systems with reduced symmetry. , 2007, Physical review letters.

[11]  D. Ralph,et al.  Interface-Induced Phenomena in Magnetism. , 2016, Reviews of modern physics.

[12]  Luis Morellón,et al.  Control of the spin to charge conversion using the inverse Rashba-Edelstein effect , 2015 .

[13]  H. Nakayama,et al.  Rashba-Edelstein Magnetoresistance in Metallic Heterostructures. , 2016, Physical review letters.

[14]  Self-induced inverse spin Hall effect in permalloy at room temperature , 2013, 1301.3580.

[15]  Observation of inverse Edelstein effect in Rashba-split 2DEG between SrTiO3 and LaAlO3 at room temperature , 2016, Science Advances.

[16]  R. Duine,et al.  New perspectives for Rashba spin-orbit coupling. , 2015, Nature materials.

[17]  Yu Fu,et al.  Highly efficient and tunable spin-to-charge conversion through Rashba coupling at oxide interfaces. , 2016, Nature materials.

[18]  S. Rezende,et al.  Addition and subtraction of spin pumping voltages in magnetic hybrid structures , 2014 .

[19]  T. Silva,et al.  Detection of the DC Inverse Spin Hall Effect Due to Spin Pumping in a Novel Meander-Stripline Geometry , 2014, IEEE Magnetics Letters.

[20]  G. Vignale,et al.  Origin of inverse Rashba-Edelstein effect detected at the Cu/Bi interface using lateral spin valves , 2014, 1409.8540.

[21]  Virginia O. Lorenz,et al.  Quantifying interface and bulk contributions to spin–orbit torque in magnetic bilayers , 2014, Nature Communications.

[22]  J. Pearson,et al.  Enhanced spin signals due to native oxide formation in Ni80Fe20/Ag lateral spin valves , 2010 .

[23]  A. Fert,et al.  Spin-to-charge conversion using Rashba coupling at the interface between non-magnetic materials , 2013, Nature Communications.

[24]  G. Jakob,et al.  Efficient metallic spintronic emitters of ultrabroadband terahertz radiation , 2016 .

[25]  E. Ivchenko,et al.  New photogalvanic effect in gyrotropic crystals , 1978 .

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

[27]  M. Cinchetti,et al.  Engineered materials for all-optical helicity-dependent magnetic switching. , 2014, Nature materials.

[28]  T. Rasing,et al.  All-optical magnetic recording with circularly polarized light. , 2007, Physical review letters.

[29]  A. Fert,et al.  Emergent phenomena induced by spin–orbit coupling at surfaces and interfaces , 2016, Nature.

[30]  J. Pearson,et al.  Perspective: Interface generation of spin-orbit torques , 2016 .

[31]  F. Freimuth,et al.  Terahertz spin current pulses controlled by magnetic heterostructures. , 2012, Nature nanotechnology.

[32]  P. Freitas,et al.  Femtosecond control of electric currents in metallic ferromagnetic heterostructures. , 2015, Nature nanotechnology.