Enhanced spin-to-charge current conversion at metal/oxide interfaces by lowering the temperature
TL;DR: In this paper, the temperature dependence of spin-to-charge current conversion at nonmagnetic metal (NM: Cu or Ag)/Bi2O3 interfaces with Rashba spin-splitting was investigated in the temperature range from 290 K to 10 K.
Abstract: We have investigated the temperature dependence of spin-to-charge current conversion at nonmagnetic metal (NM: Cu or Ag)/Bi2O3 interfaces with Rashba spin-splitting. Spin pumping induced inverse Edelstein effects are measured in the temperature range from 290 K to 10 K. Estimated conversion coefficients at the Cu(Ag)/Bi2O3 interfaces are increased by 40(17)% at 10 K compared with at 290 K. The conversion coefficient is found proportional to the conductivity of NM layer, indicating that the momentum relaxation process in the metal layer dominates in the spin-to-charge current conversion process at NM/Bi2O3 interfaces.
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Journal Article•
TL;DR: This work presents experiments evidencing a large spin-charge conversion by the Bi/Ag Rashba interface and demonstrates that the Rashba effect at interfaces can be used for efficient charge-spin conversion in spintronics.
Abstract: 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.
37 citations
TL;DR: In this article, a universal theoretical framework for the description of spin-charge interconversion in non-magnetic metal/insulator structures with interfacial spin-orbit coupling (ISOC) is presented and experimentally verified.
Abstract: We present and experimentally verify a universal theoretical framework for the description of spin-charge interconversion in non-magnetic metal/insulator structures with interfacial spin–orbit coupling (ISOC). Our formulation is based on drift-diffusion equations supplemented with generalized boundary conditions. The latter encode the effects of ISOC and relate the electronic transport in such systems to spin loss and spin-charge interconversion at the interface. We demonstrate that the conversion efficiency depends solely on these interfacial parameters. We apply our formalism to two typical spintronic devices that exploit ISOC: a lateral spin valve and a multilayer Hall bar, for which we calculate the non-local resistance and the spin Hall magnetoresistance, respectively. Finally, we perform measurements on these two devices with a BiOx/Cu interface and verify that transport properties related to the ISOC are quantified by the same set of interfacial parameters.
15 citations
TL;DR: In this paper, the spin pumping effect of Y3Fe5O12 (YIG)/Cu (tCu nm)/Cr heterostructures at room temperature with the thickness of the Cu interlayer varying from 0.4 nm to 5.0
Abstract: Here, we have investigated the spin pumping effect of Y3Fe5O12 (YIG)/Cu (tCu nm)/Cr heterostructures at room temperature with the thickness of the Cu interlayer varying from 0.4 nm to 5.0 nm. A huge charge signal Ic = 0.239 μA is observed in a YIG/Cr bilayer with direct contact, whereas Ic drops dramatically by two orders of magnitude when thin Cu interlayers down to 0.4 nm are inserted between YIG and Cr. Meanwhile, the injected spin current Js stays almost invariant for all the heterostructures. The effective spin Hall angle “θSH” of the YIG/Cr interface is found to be three orders of magnitude larger than the spin Hall angle θSH of the bulk Cr layer in YIG/Cu/Cr. The huge spin-charge conversion efficiency at the YIG/Cr interface is attributed to the inverse Rashba–Edelstein effect. Our experimental results demonstrate the dominant role of the interfacial effect in the spin-charge conversion process of the YIG/Cr heterostructures.
14 citations
Posted Content•
TL;DR: In this paper, a universal theoretical framework for the description of spin-charge interconversion in non-magnetic metal/insulator structures with interfacial spin-orbit coupling (ISOC) is presented.
Abstract: We present and verify experimentally a universal theoretical framework for the description of spin-charge interconversion in non-magnetic metal/insulator structures with interfacial spin-orbit coupling (ISOC). Our formulation is based on drift-diffusion equations supplemented with generalized boundary conditions. The latter encode the effects of ISOC and relate the electronic transport in such systems to spin loss and spin-charge interconversion at the interface, which are parameterized, respectively, by $G_{\parallel/\perp}$ and $\sigma_{\rm{sc/cs}}$. We demonstrate that the conversion efficiency depends solely on these interfacial parameters. We apply our formalism to two typical spintronic devices that exploit ISOC: a lateral spin valve and a multilayer Hall bar, for which we calculate the non-local resistance and the spin Hall magnetoresistance, respectively. Finally, we perform measurements on these two devices with a BiO$_x$/Cu interface and verify that transport properties related to the ISOC are quantified by the same set of interfacial parameters.
4 citations
Dissertation•
03 Feb 2021
TL;DR: In this paper, the authors study the interacciones of espin-orbita in two ramas mas prometedoras of the fisica of hoy en dia, the espintronica and the nanofotonica.
Abstract: En esta Tesis, estudiamos los fundamentos teoricos de las interacciones de espin-orbita en dos de las ramas mas prometedoras de la fisica de hoy en dia, la espintronica y la nanofotonica. Nos enfocamos en entender las posibles analogias entre ambas ramas y en la busqueda de un posible lenguaje y modelo comun para describir las interacciones de espin-orbita. El punto de partida comun son las interacciones de espin-orbita que aparecen en problemas de dispersion tanto de electrones como de radiacion electromagnetica en impurezas aisladas. A partir de este estudio inicial, pasamos a profundizar en las interacciones en ambas ramas por separado.En la parte de nanofotonica, la accesibilidad de los experimentos de dispersion de impurezas aisladas y la falta de estudio basico en las interacciones de espin-orbita en luz, hacen que hoy en dia siga siendo un campo con intensa investigacion. Concretamente, estudiamos los efectos de la interaccion entre el momento dipolar electrico y magnetico en la dispersion de onda plana de una particula dielectrica con indice de refraccion alto. Como consecuencia de la transferencia entre el momento angular de espin y orbital, demostramos la aparicion de errores de localizacion divergentes en la deteccion de campo lejano.En la rama de espintronica, en cambio, el concepto de acoplo de espin-orbita y sus consecuencias estan bien establecidos. Los estudios hoy en dia, por tanto, se basan en transporte electronico, en los que los efectos de espin-orbita de dispersion con impurezas han de sumarse a los del acoplo espin-orbita intrinseco o los del desorden. Concretamente, en esta tesis nos enfocamos en dispositivos hibridos, con regiones con acoplo espin-orbita adyacentes a regiones sin tal acoplo. En este sentido, ofrecemos la descripcion de sistemas hibridos en los que las ecuaciones de difusion de espin y carga han de resolverse con ayuda de condiciones de frontera.Gracias al estudio teorico desarrollado en esta tesis en ambas ramas de la fisica, hemos tenido la oportunidad de contribuir con diferentes publicaciones que forman parte de esta Tesis por compendio de articulos.
References
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TL;DR: In this article, a pure spin current was injected into a Pt thin film using spin pumping, and it was observed to generate electromotive force transverse to the spin current, consistent with the spin-Hall effect.
Abstract: The inverse process of the spin-Hall effect (ISHE), conversion of a spin current into an electric current, was observed at room temperature. A pure spin current was injected into a Pt thin film using spin pumping, and it was observed to generate electromotive force transverse to the spin current. By changing the spin-current polarization direction, the magnitude of this electromotive force varies critically, consistent with the prediction of ISHE.
1,835 citations
TL;DR: The precession of the magnetization of a ferromagnet is shown to transfer spins into adjacent normal metal layers, slowing down the precession corresponding to an enhanced Gilbert damping constant in the Landau-Lifshitz equation.
Abstract: The precession of the magnetization of a ferromagnet is shown to transfer spins into adjacent normal metal layers. This ``pumping'' of spins slows down the precession corresponding to an enhanced Gilbert damping constant in the Landau-Lifshitz equation. The damping is expressed in terms of the scattering matrix of the ferromagnetic layer, which is accessible to model and first-principles calculations. Our estimates for permalloy thin films explain the trends observed in recent experiments.
1,558 citations
TL;DR: In this article, the spin Hall effect in a thin film with strong spin-orbit scattering can excite magnetic precession in an adjacent ferromagnetic film, and the ratio of these two signals allows a quantitative determination of the spin current and spin Hall angle.
Abstract: We demonstrate that the spin Hall effect in a thin film with strong spin-orbit scattering can excite magnetic precession in an adjacent ferromagnetic film. The flow of alternating current through a Pt/NiFe bilayer generates an oscillating transverse spin current in the Pt, and the resultant transfer of spin angular momentum to the NiFe induces ferromagnetic resonance dynamics. The Oersted field from the current also generates a ferromagnetic resonance signal but with a different symmetry. The ratio of these two signals allows a quantitative determination of the spin current and the spin Hall angle.
1,421 citations
1,085 citations
TL;DR: A new example of an electronic property arising from the interfacial breaking of inversion symmetry, namely, a large Rashba spin-orbit interaction, whose magnitude can be modulated by the application of an external electric field is laid out.
Abstract: The quasi-two-dimensional electron gas found at the ${\mathrm{LaAlO}}_{3}/{\mathrm{SrTiO}}_{3}$ interface offers exciting new functionalities, such as tunable superconductivity, and has been proposed as a new nanoelectronics fabrication platform. Here we lay out a new example of an electronic property arising from the interfacial breaking of inversion symmetry, namely, a large Rashba spin-orbit interaction, whose magnitude can be modulated by the application of an external electric field. By means of magnetotransport experiments we explore the evolution of the spin-orbit coupling across the phase diagram of the system. We uncover a steep rise in Rashba interaction occurring around the doping level where a quantum critical point separates the insulating and superconducting ground states of the system.
787 citations