Quantifying Spin Hall Angles from Spin Pumping: Experiments and Theory

Mosendz, O.; Pearson, John; Fradin, F. Y.; Bauer, G.; Bader, S. D.; Hoffmann, A.

doi:10.1103/physrevlett.104.046601

Cited by 665 publications

(712 citation statements)

References 31 publications

(47 reference statements)

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“…Conversely, when magnetization dynamics in the ferromagnet are excited, the normal metal provides an additional magnetization damping channel, a process which can be described as injection of a pure spin current from the ferromagnet into the normal metal. The inverse spin Hall effect makes detection of this spin current generated by spin pumping [15] possible in terms of a dc inverse spin Hall voltage V SP [26]. V SP is a measure of the power absorbed by the magnetic system and therefore yields a purely symmetric resonance line shape [26], irrespective of the origin of the magnetization precession.…”

Section: Theorymentioning

confidence: 99%

“…The inverse spin Hall effect makes detection of this spin current generated by spin pumping [15] possible in terms of a dc inverse spin Hall voltage V SP [26]. V SP is a measure of the power absorbed by the magnetic system and therefore yields a purely symmetric resonance line shape [26], irrespective of the origin of the magnetization precession.…”

Section: Theorymentioning

confidence: 99%

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Current-induced spin torque resonance of a magnetic insulator

et al. 2015

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We report the observation of current-induced spin torque resonance in yttrium iron garnet/platinum bilayers. An alternating charge current at GHz frequencies in the platinum gives rise to dc spin pumping and spin Hall magnetoresistance rectification voltages, induced by the Oersted fields of the ac current and the spin Hall effect-mediated spin transfer torque. In ultrathin yttrium iron garnet films, we observe spin transfer torque actuated magnetization dynamics which are significantly larger than those generated by the ac Oersted field. Spin transfer torques thus efficiently couple charge currents and magnetization dynamics also in magnetic insulators, enabling charge current-based interfacing of magnetic insulators with microwave devices.

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Current-induced spin torque resonance of a magnetic insulator

et al. 2015

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“…1c). Whereas in static experiments the resulting charge current is measured as a voltage 14,15,24 , we here electrooptically sample the field of the electromagnetic pulse that is emitted by the charge current burst j c (see Fig. 1a and Methods).…”

mentioning

confidence: 99%

“…This modulation leads to the emission of magnetic dipole radiation 28,29,30,31 and the generation of an additional spin current along z via spin pumping 6,24 .…”

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confidence: 99%

Terahertz spin current pulses controlled by magnetic heterostructures

et al. 2013

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In spin-based electronics, information is encoded by the spin state of electron bunches 1,2,3,4 . Processing this information requires the controlled transport of spin angular momentum through a solid 5,6 , preferably at frequencies reaching the so far unexplored terahertz (THz) regime 7,8,9 . Here, we demonstrate, by experiment and theory, that the temporal shape of femtosecond spin-current bursts can be manipulated by using specifically designed magnetic heterostructures. A laser pulse is employed to drive spins 10,11,12 from a ferromagnetic Fe thin film into a nonmagnetic cap layer that has either low (Ru) or high (Au) electron mobility. The resulting transient spin current is detected by means of an ultrafast, contactless amperemeter 13 based on the inverse spin Hall effect 14,15 that converts the spin flow into a THz electromagnetic pulse. We find that the Ru cap layer yields a considerably longer spin-current pulse because electrons are injected in Ru d states that have a much smaller mobility than Au sp states 16 . Thus, spin current pulses and the resulting THz transients can be shaped by tailoring magnetic heterostructures, which opens the door for engineering high-speed spintronic devices as well as broadband THz emitters 7,8,9 , in particular covering the elusive range from 5 to 10THz.Contemporary electronics is based on the electron charge as information carrier whose presence or absence encodes the value of a bit. Much more efficient devices for low-power data storage and processing could be realized if the spin degree of freedom were used in addition 1,2,3,4 . The spintronics approach requires the generation and control of spin currents, that is, the transport of spin angular momentum through space 5,6 . Spintronic operations should be performed at a pace exceeding that of today's computers, which ultimately requires the generation of spin current pulses with terahertz (1 THz = 10 12 Hz) bandwidths 7,8 as well as the possibility to manipulate them in novel structures 17,18 . To date, femtosecond spin-current pulses have been successfully launched by optically exciting electrons in semiconductors 10 or ferromagnetic metals 11,12 . However, to enable ultrafast basic operations on these transients (such as buffering or delaying), their shape and propagation have to be controlled on subpicosecond time scales.Here, we employ magnetic heterostructures containing an optimally chosen nonmagnetic metallic layer whose electron mobility allows us either to trap or to transmit electrons and, thus, to engineer ultrafast spin pulses. The spin flow is probed in a contactless manner using the inverse spin Hall effect 14,15 (ISHE) that converts the spin current into a detectable THz electromagnetic pulse 13 . Our findings open up a route to device-oriented femtosecond spintronics as well as novel broadband emitters of THz radiation 7,8,9 .Our idea is illustrated in Fig. 1a, which shows a schematic of a ferromagnetic Fe film capped by a thin layer of Ru or Au. Absorption of a femtosecond laser pulse (photon energy 1...

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“…The effective interfacial spin mixing conductance g ↑↓ eff can be determined 2,3 from: 43,44 that reflects significant spin transport across the Pt/LSMO interface despite of the ex situ deposition of Pt. For direct confirmation of the spin pumping process, we measure direct voltage induced in the Pt film via the inverse spin Hall effect (ISHE).…”

Section: -5mentioning

confidence: 99%

Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

et al. 2016

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We report ferromagnetic resonance measurements of magnetic anisotropy and damping in epitaxial La0.7Sr0.3MnO3 (LSMO) and Pt capped LSMO thin films on SrTiO3 (001) substrates. The measurements reveal large negative perpendicular magnetic anisotropy and a weaker uniaxial in-plane anisotropy that are unaffected by the Pt cap. The Gilbert damping of the bare LSMO films is found to be low α = 1.9(1) × 10−3, and two-magnon scattering is determined to be significant and strongly anisotropic. The Pt cap increases the damping by 50% due to spin pumping, which is also directly detected via inverse spin Hall effect in Pt. Our work demonstrates efficient spin transport across the Pt/LSMO interface.

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Quantifying Spin Hall Angles from Spin Pumping: Experiments and Theory

Cited by 665 publications

References 31 publications

Current-induced spin torque resonance of a magnetic insulator

Current-induced spin torque resonance of a magnetic insulator

Terahertz spin current pulses controlled by magnetic heterostructures

Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

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