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Journal ArticleDOI

Inverse Spin Hall Effect in nanometer-thick YIG/Pt system

TL;DR: Inverse spin Hall effect (ISHE) detection of propagating spin waves using Pt. as discussed by the authors has been shown to correlate well with the increase of the Gilbert damping when decreasing thickness of YIG.
Abstract: High quality nanometer-thick (20 nm, 7 nm and 4 nm) epitaxial YIG films have been grown on GGG substrates using pulsed laser deposition. The Gilbert damping coefficient for the 20 nm thick films is 2.3 x 10-4 which is the lowest value reported for sub-micrometric thick films. We demonstrate Inverse spin Hall effect (ISHE) detection of propagating spin waves using Pt. The amplitude and the lineshape of the ISHE voltage correlate well to the increase of the Gilbert damping when decreasing thickness of YIG. Spin Hall effect based loss-compensation experiments have been conducted but no change in the magnetization dynamics could be detected.
Citations
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Journal ArticleDOI
TL;DR: This topical review addresses materials with a periodic modulation of magnetic parameters that give rise to artificially tailored band structures and allow unprecedented control of spin waves in microand nanostructured ferromagnetic materials.
Abstract: Research efforts addressing spin waves (magnons) in micro- and nanostructured ferromagnetic materials have increased tremendously in recent years. Corresponding experimental and theoretical work in magnonics faces significant challenges in that spin-wave dispersion relations are highly anisotropic and different magnetic states might be realized via, for example, the magnetic field history. At the same time, these features offer novel opportunities for wave control in solids going beyond photonics and plasmonics. In this topical review we address materials with a periodic modulation of magnetic parameters that give rise to artificially tailored band structures and allow unprecedented control of spin waves. In particular, we discuss recent achievements and perspectives of reconfigurable magnonic devices for which band structures can be reprogrammed during operation. Such characteristics might be useful for multifunctional microwave and logic devices operating over a broad frequency regime on either the macro- or nanoscale.

535 citations

Journal ArticleDOI
TL;DR: In this article, different approaches for the realization of static, reconfigurable, and dynamic magnonic crystals are presented along with a variety of novel wave phenomena discovered in these crystals.
Abstract: Magnons—the quanta of spin waves—propagating in magnetic materials with wavelengths at the nanometer-scale and carrying information in the form of an angular momentum, can be used as data carriers in next-generation, nano-sized low-loss information processing systems. In this respect, artificial magnetic materials with properties periodically varied in space, known as magnonic crystals, are especially promising for controlling and manipulating the magnon currents. In this article, different approaches for the realization of static, reconfigurable, and dynamic magnonic crystals are presented along with a variety of novel wave phenomena discovered in these crystals. Special attention is devoted to the utilization of magnonic crystals for processing of analog and digital information. Magnonic crystals for data processing 2

353 citations

Journal ArticleDOI
TL;DR: In this article, a unique feature of the band structure has been exploited to achieve similar levels of magnetic damping in a metallic alloy, which is important for a range of applications but is typically insulating.
Abstract: Materials with low magnetic damping are important for a range of applications but are typically insulating, which limits their use. Thanks to a unique feature of the band structure, similar levels of damping can now be achieved in a metallic alloy.

299 citations

Journal ArticleDOI
TL;DR: In this article, a 22nm-thick yttrium iron garnet (YIG) film with a Gilbert damping constant α = (8.58 ± 0.21) × 10 -5
Abstract: Yttrium iron garnet (YIG) films that are in the nanometer thickness range and show extremely low damping are reported. The films were deposited via sputtering at room temperature and were then annealed in O 2 at high temperature. A 22-nm-thick YIG film showed a Gilbert damping constant α = (8.58 ± 0.21) × 10 -5 , which represents the lowest damping ever reported for nanometer-thick magnetic films. The film had a gyromagnetic ratio of |γ| = 2.83 MHz/Oe and a saturation induction of 4π M s = 1766 G, which are both very close to those of single-crystal YIG bulk materials. The film had a very smooth surface, with an rms surface roughness of about 0.13 nm.

265 citations

Journal ArticleDOI
TL;DR: It is demonstrated that nm-thick YIG films overcome the damping chasm and are expected to provide the basis for coherent data processing with SWs at GHz rates and in large arrays of cellular magnetic arrays, thereby boosting the envisioned image processing and speech recognition.
Abstract: Wave control in the solid state has opened new avenues in modern information technology. Surface-acoustic-wave-based devices are found as mass market products in 100 millions of cellular phones. Spin waves (magnons) would offer a boost in today's data handling and security implementations, i.e., image processing and speech recognition. However, nanomagnonic devices realized so far suffer from the relatively short damping length in the metallic ferromagnets amounting to a few 10 micrometers typically. Here we demonstrate that nm-thick YIG films overcome the damping chasm. Using a conventional coplanar waveguide we excite a large series of short-wavelength spin waves (SWs). From the data we estimate a macroscopic of damping length of about 600 micrometers. The intrinsic damping parameter suggests even a record value about 1 mm allowing for magnonics-based nanotechnology with ultra-low damping. In addition, SWs at large wave vector are found to exhibit the non-reciprocal properties relevant for new concepts in nanoscale SW-based logics. We expect our results to provide the basis for coherent data processing with SWs at GHz rates and in large arrays of cellular magnetic arrays, thereby boosting the envisioned image processing and speech recognition.

220 citations

References
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Journal ArticleDOI
TL;DR: In this paper, it is proposed that when a charge current circulates in a paramagnetic metal, a transverse spin imbalance will be generated, giving rise to a spin Hall voltage, in the absence of charge current and magnetic field.
Abstract: It is proposed that when a charge current circulates in a paramagnetic metal a transverse spin imbalance will be generated, giving rise to a ``spin Hall voltage.'' Similarly, it is proposed that when a spin current circulates a transverse charge imbalance will be generated, giving rise to a Hall voltage, in the absence of charge current and magnetic field. Based on these principles we propose an experiment to generate and detect a spin current in a paramagnetic metal.

2,337 citations

Journal ArticleDOI
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

01 Mar 2001
TL;DR: In this article, it is proposed that when a charge current circulates in a paramagnetic metal, a transverse spin imbalance will be generated, giving rise to a spin Hall voltage, in the absence of charge current and magnetic field.
Abstract: It is proposed that when a charge current circulates in a paramagnetic metal a transverse spin imbalance will be generated, giving rise to a ``spin Hall voltage.'' Similarly, it is proposed that when a spin current circulates a transverse charge imbalance will be generated, giving rise to a Hall voltage, in the absence of charge current and magnetic field. Based on these principles we propose an experiment to generate and detect a spin current in a paramagnetic metal.

1,765 citations

Journal ArticleDOI
11 Mar 2010-Nature
TL;DR: It is shown that a spin wave in an insulator can be generated and detected using spin-Hall effects, which enable the direct conversion of an electric signal into aspin wave, and its subsequent transmission through (and recovery from) an insulators over macroscopic distances.
Abstract: An insulator does not conduct electricity, and so cannot in general be used to transmit an electrical signal. However, the electrons within an insulator possess spin as well as charge, so it is possible for them to transmit a signal in the form of a spin wave. Kajiwara et al. have now developed a hybrid metal–insulator–metal structure in which an electrical signal in one metal layer is directly converted to a spin wave in the insulating layer. This wave is then transmitted to the second metal layer, where the signal can be directly recovered as an electrical voltage. The observation of voltage transmission in an insulator raises the prospect of insulator-based spintronics and other novel forms of signal delivery. An insulator does not conduct electricity, and so cannot in general be used to transmit an electrical signal. But an insulator's electrons possess spin in addition to charge, and so can transmit a signal in the form of a spin wave. Here a hybrid metal–insulator–metal structure is reported, in which an electrical signal in one metal layer is directly converted to a spin wave in the insulating layer; this wave is then transmitted to the second metal layer, where the signal can be directly recovered as an electrical voltage. The energy bandgap of an insulator is large enough to prevent electron excitation and electrical conduction1. But in addition to charge, an electron also has spin2, and the collective motion of spin can propagate—and so transfer a signal—in some insulators3. This motion is called a spin wave and is usually excited using magnetic fields. Here we show that a spin wave in an insulator can be generated and detected using spin-Hall effects, which enable the direct conversion of an electric signal into a spin wave, and its subsequent transmission through (and recovery from) an insulator over macroscopic distances. First, we show evidence for the transfer of spin angular momentum between an insulator magnet Y3Fe5O12 and a platinum film. This transfer allows direct conversion of an electric current in the platinum film to a spin wave in the Y3Fe5O12 via spin-Hall effects4,5,6,7,8,9,10,11. Second, making use of the transfer in a Pt/Y3Fe5O12/Pt system, we demonstrate that an electric current in one metal film induces voltage in the other, far distant, metal film. Specifically, the applied electric current is converted into spin angular momentum owing to the spin-Hall effect7,8,10,11 in the first platinum film; the angular momentum is then carried by a spin wave in the insulating Y3Fe5O12 layer; at the distant platinum film, the spin angular momentum of the spin wave is converted back to an electric voltage. This effect can be switched on and off using a magnetic field. Weak spin damping3 in Y3Fe5O12 is responsible for its transparency for the transmission of spin angular momentum. This hybrid electrical transmission method potentially offers a means of innovative signal delivery in electrical circuits and devices.

1,391 citations

Journal ArticleDOI
TL;DR: Using spin torque induced ferromagnetic resonance with a β-W/CoFeB bilayer microstrip, the spin Hall angle was determined to be |θSHβ-W|=0.30±0.02 as mentioned in this paper.
Abstract: We report a giant spin Hall effect in β-W thin films. Using spin torque induced ferromagnetic resonance with a β-W/CoFeB bilayer microstrip, we determine the spin Hall angle to be |θSHβ-W|=0.30±0.02, large enough for an in-plane current to efficiently reverse the orientation of an in-plane magnetized CoFeB free layer of a nanoscale magnetic tunnel junction adjacent to a thin β-W layer. From switching data obtained with such 3-terminal devices, we independently determine |θSHβ-W|=0.33±0.06. We also report variation of the spin Hall switching efficiency with W layers of different resistivities and hence of variable (α and β) phase composition.

1,128 citations