Spectral shape deformation in inverse spin Hall voltage in Y3Fe5O12|Pt bilayers at high microwave power levels

Lustikova, J.; Shiomi, Yuki; Handa, Yasunobu; Saitoh, Eiji

doi:10.1063/1.4908211

Cited by 7 publications

(13 citation statements)

References 34 publications

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“…This value is much larger than the temperature rise found in FMR measurements of micrometer-thick YIG slabs and spin-pumping experiments. 33,35 This observation is reasonable since the microwave signal in our experiment is passed through the Pt layer that is in direct contact to the YIG nanowire, whereas in FMR and spin-pumping experiments an antenna or cavity is used to excite the spin dynamics. We do not only observe unusual behavior of the resonant signal, but also of the off-resonant voltage caused by the longitudinal SSE visible as an offset in Fig.…”

Section: Resultsmentioning

confidence: 77%

Insulating Nanomagnets Driven by Spin Torque

et al. 2016

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Magnetic insulators, such as yttrium iron garnet (YFeO), are ideal materials for ultralow power spintronics applications due to their low energy dissipation and efficient spin current generation and transmission. Recently, it has been realized that spin dynamics can be driven very effectively in micrometer-sized YFeO/Pt heterostructures by spin-Hall effects. We demonstrate here the excitation and detection of spin dynamics in YFeO/Pt nanowires by spin-torque ferromagnetic resonance. The nanowires defined via electron-beam lithography are fabricated by conventional room temperature sputtering deposition on GdGaO substrates and lift-off. We observe field-like and antidamping-like torques acting on the magnetization precession, which are due to simultaneous excitation by Oersted fields and spin-Hall torques. The YFeO/Pt nanowires are thoroughly examined over a wide frequency and power range. We observe a large change in the resonance field at high microwave powers, which is attributed to a decreasing effective magnetization due to microwave absorption. These heating effects are much more pronounced in the investigated nanostructures than in comparable micron-sized samples. By comparing different nanowire widths, the importance of geometrical confinements for magnetization dynamics becomes evident: quantized spin-wave modes across the width of the wires are observed in the spectra. Our results are the first stepping stones toward the realization of integrated magnonic logic devices based on insulators, where nanomagnets play an essential role.

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Section: Resultsmentioning

confidence: 77%

Insulating Nanomagnets Driven by Spin Torque

et al. 2016

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“…Finally, it should be noted that the foldover effect presented above differs from that observed previously for ferromagnetic resonance in magnetic thin films. In this work the foldover effect is associated with the nonlinear frequency shift of traveling spin waves, while in previous work the effect was for spatially uniform precessions of magnetic moments [21,22,23,25].…”

mentioning

confidence: 70%

“…Four important points should be highlighted. First, the foldover effects reported previously are associated with the nonlinearity-caused frequency shift of simple, local oscillations [18][19][20][21][22][23], while the foldover effect presented below results from the nonlinear frequency shift of waves traveling around a feedback ring. This indicates that the foldover effect not only occurs for local oscillations but also for traveling waves.…”

mentioning

confidence: 97%

“…The nonlinear foldover effect originates from the nonlinearity in which the oscillation frequency varies with the amplitude, and manifests itself as the bending of the resonant peak in an oscillation amplitude vs. frequency plot. It occurs in nonlinear systems as diverse as driven pendula [18], spring-based mechanical oscillators [19], electrical RLC resonant circuits [20], and precessional magnetic moments in both insulating and metallic magnets [21,22,23]. The effect, however, has never been observed in ring systems so far.…”

mentioning

confidence: 99%

“…This hysteresis response was not measured as the frequency sweeping direction was limited in the experiment. However, it is intrinsic [19,22,23] and can easily be imaged with the help of the foldover shown in Fig. 4(b).…”

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confidence: 99%

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Foldover of nonlinear eigenmodes in magnetic thin film based feedback rings

Janantha

Kalinikos

2017

Phys. Rev. B

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The foldover effect of nonlinear eigenmodes in feedback ring systems was observed for the first time. Experiments made use of a system that consisted of a magnetic thin film strip, which supported the propagation of spin waves, and a microwave amplifier, which amplified the signal from the output of the magnetic strip and then fed it back to the input of the magnetic strip. The signal amplitude vs. frequency response in this ring system showed resonant peaks which resulted from ring eigenmodes. With an increase in the resonance amplitude, those resonant peaks evolved from symmetric peaks to asymmetric ones and then folded over to higher frequencies. The experimental observations were reproduced by theoretical calculations that took into account the nonlinearity-produced frequency shift of the traveling spin waves.

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Generation of megahertz-band spin currents using nonlinear spin pumping

Watanabe

Hirobe

Shiomi

et al. 2017

Sci Rep

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Spin pumping enables the generation of d.c. and gigahertz-band (GHz-band) voltages from an applied microwave via magnetization dynamics when combined with inverse spin Hall effects. However, generating such voltages in the in-between frequency region, or the megahertz (MHz) band, has been difficult since ferromagnetic resonance usually occurs in the GHz band. Here we show that in spite of GHz-band microwaves applied, MHz-band voltages can be generated by spin pumping with use of nonlinear magnetization dynamics in Y3Fe5O12. The mechanism is ascribed to the MHz-band oscillation of the amplitude of the magnetization precession, which is projected onto a rectified voltage component via spin pumping. The present finding could be useful for frequency down-conversion thanks to the simple and durable structure, continuous-wave operation, and the tunability of an output frequency with low magnetic fields.

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Spectral shape deformation in inverse spin Hall voltage in Y3Fe5O12|Pt bilayers at high microwave power levels

Cited by 7 publications

References 34 publications

Insulating Nanomagnets Driven by Spin Torque

Insulating Nanomagnets Driven by Spin Torque

Foldover of nonlinear eigenmodes in magnetic thin film based feedback rings

Generation of megahertz-band spin currents using nonlinear spin pumping

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