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Title: Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 119; Journal Issue: 2; Related Information: CHORUS Timestamp: 2017-07-14 22:11:08; Journal ID: ISSN 0031-9007
American Physical Society
Country of Publication:
United States

Citation Formats

Janantha, P. A. Praveen, Sprenger, Patrick, Hoefer, Mark A., and Wu, Mingzhong. Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.119.024101.
Janantha, P. A. Praveen, Sprenger, Patrick, Hoefer, Mark A., & Wu, Mingzhong. Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films. United States. doi:10.1103/PhysRevLett.119.024101.
Janantha, P. A. Praveen, Sprenger, Patrick, Hoefer, Mark A., and Wu, Mingzhong. 2017. "Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films". United States. doi:10.1103/PhysRevLett.119.024101.
title = {Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films},
author = {Janantha, P. A. Praveen and Sprenger, Patrick and Hoefer, Mark A. and Wu, Mingzhong},
abstractNote = {},
doi = {10.1103/PhysRevLett.119.024101},
journal = {Physical Review Letters},
number = 2,
volume = 119,
place = {United States},
year = 2017,
month = 7

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on July 14, 2018
Publisher's Accepted Manuscript

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  • The end edge reflection and collision of backward volume wave bright microwave magnetic envelope solitons in long and narrow yttrium iron garnet single-crystal films has been studied experimentally. The experiments were done on 5.1-{mu}m-thick, 1-mm-wide films. The bright solitons were excited by single or double 8{endash}36-ns-wide microwave pulses with a nominal carrier frequency of 5.8 GHz. The experiments utilized a movable transducer structure to make measurements for a range of transducer separations from 2 to 15 mm and for pulses before and after reflection. The soliton character was established from single-pulse decay versus time and distance measurements. Three decay regionsmore » were observed, a slow decay region before soliton formation, a fast decay region characteristic of solitons, and a second slow decay for linear pulses. The soliton region included both incident and reflected pulses. The exponential decay rate for the soliton regime was greater than for the linear. The soliton pulses retained the same shape and speed after edge reflection. An observed drop in pulse amplitude after passing under the pickup transducer provided a way to measure the actual power and amplitude of the soliton signal. The measured amplitudes and widths were in fair agreement with predictions for a simple sech-type order one soliton pulse. For properly timed double-pulse experiments in which a reflected lead pulse collides with the follow-on pulse before detection, the effects of soliton collisions could be examined. In the single soliton power regime, the pulses were found to retain their shape and speed after collision. At higher powers, shapes were not retained. In addition, a wake effect was observed in which the lead pulse causes a change in the detected signal for the follow-on pulse, even without collision. {copyright} {ital 1996 The American Physical Society.}« less
  • Microwave magnetic envelope (MME) wave-packet propagation in a 7.2-{mu}m-thick yttrium iron garnet film has been investigated to determine the decay properties of linear and nonlinear MME pulses. The data were obtained in the magnetostatic backward volume wave configuration with an in-plane static field of 1088 Oe and an operating frequency of 5 GHz. Output pulse profiles, peak powers, and integrated pulse energies were measured for 13 ns wide input pulses and propagation distances from 3 to 10 mm. The pulse energy decay rate {beta} is found to be 10.6{times}10{sup 6} rad/s and independent of the input power level up tomore » 400 mW, even though the nonlinear response begins at 80 mW. This {beta} value is twice the relaxation rate {eta} from ferromagnetic resonance. In the linear regime below 80 mW, the amplitude decay rate {alpha} of the dynamic microwave magnetization peak amplitude is nearly constant at a value {alpha}{sub low}{approx}7.8{times}10{sup 6} rad/s, somewhat greater than {beta}/2 and significantly less than {beta}. This {alpha}{sub low} is greater than the decay rate due to damping, {eta}={beta}/2, because of dispersion. With the onset of the nonlinear soliton response above 80 mW, {alpha} gradually increases and saturates for input powers greater than 200 mW at a value {alpha}{sub high} equal to the energy decay rate {beta}. This result indicates that the amplitude decay rate for MME solitons is very close to twice the relaxation rate. This result is predicted in the limit of a vanishingly small damping. Experimentally, it appears to be valid even when the relaxation is significant. The transition region from {alpha}{sub low} to {alpha}{sub high} has been quantitatively modeled through the nonlinear Schroedinger equation, and demonstrates an explicit change in the critical propagation length for soliton formation from 8 mm at the low power end of the transition to 3 mm at the high power end. {copyright} {ital 1997} {ital The American Physical Society}« less
  • Controlled off-stoichiometric single phase polycrystalline yttrium iron garnet (YIG) thin films have been grown by pulsed laser deposition, adjusting the oxygen partial pressure P{sub O2} between 5 and 400 mTorr. Atomic stoichiometry by RBS shows an oxygen deficiency for P{sub O2}<P{sub stoich} and iron and yttrium deficiency for P{sub O2}>P{sub stoich}. P{sub stoich}=30 mTorr refers to films showing magnetic and structural properties of the bulk stoichiometric YIG. Curie temperature T{sub c} and saturation magnetization 4{pi}Ms decreased for P{sub O2}<P{sub stoich}, whereas a new part of the YIG phase diagram is explored for P{sub O2}>P{sub stoich}: Increase of Tc (up tomore » +10%) and of 4{pi}Ms (up to +20%) and lattice parameter compression. Microscopic interpretation is given in terms of superexchange interaction and creation and site selectivity of iron vacancies.« less
  • We investigate resonant microwave absorption in films of yttrium iron garnet (YIG) with magneetic properties varying through the film thickness. Using measurements of the spin-wave resonant absorption spectra for two different directions of the external magnetic field, we calculate the profile of this nonuniformity. In our investigation of the response of nonuniform films to a pulsed microwave signal, we observed the appearance of delayed pulses, which we interpret to be the result of propagation of exchange spin waves transversely through the film. We analyze the dependence of the time delay on frequency for various nonuniformity profiles, and compare the datamore » obtained with the results of experiment. Our investigation of the spin-wave resonance spectra, as well as the results of our pulsed measurements, show that propagation of spin waves is accompanied by the excitation of acoustic waves. We conclude that ferrite films that vary in the transverse direction can on the one hand be used to efficiently excite short-wavelength exchange spin waves with wave numbers 1{approximately}3 {center_dot}10{sup 5} cm{sup {minus}1}, and on the other hand to excite very high-frequency acoustic waves. 25 refs., 15 figs.« less
  • Here, we investigated the spin-wave propagation in a micro-structured yttrium iron garnet waveguide of 40 nm thickness. Utilizing spatially-resolved Brillouin light scattering microscopy, an exponential decay of the spinwave amplitude of 10 μm was observed. This leads to an estimated Gilbert damping constant of α = (8.79 ± 0.73) x 10 $-$4, which is larger than damping values obtained through ferromagnetic resonance measurements in unstructured films. Furthermore, we compared the theoretically calculated spatial interference of waveguide modes to the spin-wave pattern observed experimentally by means of Brillouin light scattering spectroscopy.