Rayleigh Wave Attenuation Research Articles

Generation and detection of Rayleigh waves with improved attenuation using a piezo-copolymer transducer P(VDF-TrFE)

Efficient elastic Rayleigh waves have been launched and detected on a non-piezoelectric substrate (duraluminium) with identical longitudinal wave transducers made of a piezoelectric copolymer film P(VDF-TrFE). We have improved the attenuation of Rayleigh waves by more than 20 dB, by fixing the electrode spatial period in accordance with the frequency of excitation for which the elastic power transfer to the medium of propagation is at a maximum, and by electrical impedance matching at emission and reception. We also report the effect of the coupling layer thickness on the elastic power and electrical impedance of the transducer.

Acoustic microscopy measurement of elastic constants and mass density

A method is presented to determine the elastic constants and the mass density of isotropic and anisotropic solids and anisotropic thin films. The velocity and attenuation of leaky surface acoustic waves (SAWs) have been obtained for specified propagation directions from V(z) curves measured by line-focus acoustic microscopy (LFAM). The experimentally obtained velocities have been compared to velocities obtained from a measurement model for the V(z) curve which simulates the experiment. Since the measured and simulated V(z) curves have the same systemic errors, the material constants are free of such errors. For an isotropic solid, Young's modulus E, the shear modulus G and the mass density /spl rho/ have been determined from the leaky Rayleigh wave velocity and attenuation, measured by LFAM, and a longitudinal wave velocity measured by a pulse-echo transit-time technique. For a cubic-crystalline solid, the ratios of the elastic constants to the mass density (c/sub 11///spl rho/, c/sub 12///spl rho/, c/sub 44///spl rho/) have been determined from the directional variation of measured SAW velocities, using a preliminary estimate of /spl rho/. The mass density /spl rho/ has subsequently been determined by additionally using the attenuation of leaky SAWs in crystal symmetry directions. For a cubic-crystalline thin film deposited on a substrate, the elastic constants and the mass density (c/sub 11/, c/sub 12/, c/sub 44/, /spl rho/) of the film have been determined from the directional variation of the measured SAW velocities, and a comparison of the corresponding attenuation coefficient with the measured attenuation coefficient has been used to verify the results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Novel approach for detecting distributed surface-breaking cracks

A novel approach to the problem of detecting finely distributed surface cracks in a structure is proposed. The approach relies on the detection of anisotropy introduced into the surface by an oriented array of cracks and can be used for crack detection even when individual cracks in the array are below the practical threshold of detectability by conventional inspection techniques. The feasibility of detecting anisotropy associated with distributed cracking was established experimentally using: (i) a directional eddy-current probe to detect anisotropy in the effective electrical conductivity and (ii) a line-focused laser-ultrasonic source to detect anisotropy in the attenuation of ultrasonic Rayleigh waves.

Shear-wave velocity and attenuation structure beneath Antarctica determined from surface waves

SUMMARY Fundamental and higher mode surface waves generated by nine earthquakes, which occurred in Antarctica and its nearby regions and were recorded at Scott Base (SBA), South Pole (SPA), Novolazarevskaya (NVL) and Mirnyy (MIR) seismic stations are used to determine the shear-wave velocity and attenuation structure beneath these regions. The Frequency-Time Analysis method is used to determine group velocities for periods ranging from 6 to 80 seconds for fundamental and higher mode Rayleigh and Love waves. Crustal thickness is found to be 41 km beneath the eastern part and 30 km beneath the western part of Antarctica. Rayleigh and Love wave group velocities show lower values in the eastern part as compared to the western part of Antarctica. A shear-wave velocity of 3.52 to 3.7 km s−1 is estimated in the lower part of the crust (15–41 km from the surface) beneath eastern Antarctica. Similarly a shear-wave velocity of 3.48–3.6 km s−1 is estimated in the lower part of the crust (15–30 km from the surface) beneath western Antarctica. Rayleigh and Love wave group velocities are found to be lower for eastern Antarctica compared to Australia, Canada, India and other shield models of the world. Love and Rayleigh wave attenuation coefficients are estimated at periods of 10–110 s using the spectral amplitude of these waves across the eastern and western parts of Antarctica. Backus & Gilbert inversion theory is applied to the surface-wave attenuation data to obtain average Q−1β models for the crust and upper mantle beneath Antarctica. Inversion of Love and Rayleigh wave attenuation data shows a high-attenuation zone (Q= 125–200) at a depth of 10 to 40 km beneath eastern Antarctica. Similarly, a high-attenuation zone (Q= 65) occurs at a depth of 20 to 90 km beneath western Antarctica. The Q−1β models show a lithospheric thickness of 80–100 km beneath western Antarctica. The base of the lithosphere is identified as the depth at which there is a significant change in the Q−1β value. The Q−1β models for Antarctica show that there is a decrease in Q−1β value by an average of three factors in the asthenosphere as compared to lithosphere. In general, Q−1β in the asthenosphere show a higher value (an average of 2–3 times) compared to the lithosphere. This implies that the asthenosphere beneath Antarctica is cooler compared to other shield structures of the world.

On the measurement of anelastic attenuation using amplitudes of low-frequency surface waves

Abstract A method is presented for the measurement of attenuation of long-period Rayleigh waves which minimizes two effects: that of biases owing to uncertainties in the source moment tensor and that of focusing owing to propagation in a laterally heterogeneous elastic Earth. In this manner, by measuring attenuation over minor arcs, odd terms of lateral heterogeneity in Q can be resolved. Global average Q estimates are in good agreement with the Preliminary Reference Earth Model (PREM) in the period range 180–285 s. At periods shorter than 180 s, our estimates of Q are lower than predicted by PREM. Maps of lateral variations in Q −1 show a general correspondence of high Q to high shear velocity and low Q to low shear velocity. In particular, the shift to the west, at increasing period, of the locus of the minimum in the Pacific Ocean is also observed in the Q −1 maps.

Attenuation of multiphase surface waves in the Basin and Range Province-III. Inversion for crustal anelasticity

SUMMARY A combined inversion/forward modelling procedure, in which the frequency dependence of shear-wave internal friction (Qμ-1) is allowed to vary with depth, was developed and applied to selected Rayleigh wave and Lg attenuation data in the Basin and Range Province of the south-western United States. Both Q and the frequency dependence of Lg waves were used to constrain the models. Many models can explain Rayleigh wave and Lg data sets within their uncertainties, but at 1 Hz most have low values of Qμ (50-80) in the upper 8 km of the crust, rapidly increasing values to about 1000 at mid-crustal depths, and decreasing values at greater depths. Models which include a layer of higher Q values (80-150) in the upper few kilometres of the crust, overlying a region of lower Q values, cannot be precluded by the attenuation data of this study. Assuming that Qμ varies with frequency as fζ, models for which the frequency dependence is low (ζ= 0.0-0.1) in the upper crust best explain the data of this study. In the lower crust that frequency dependence is not well determined, but the models which best explain both the fundamental-mode and Lg data and produce realistic models of Qμ are characterized at 1 Hz by high values of both Qμ and its frequency dependence. Because of that frequency dependence Qμ may be an order of magnitude lower at a period of 100 s (∼ 100) than it is at 1 s (∼ 1000). Investigations of the effects of changing crustal velocity on values for Lg Q and its frequency dependence indicate that realistic velocity changes cause only small changes in those values and thus are inconsequential to our results. The low Qμ values, and their constancy with frequency, in the uppermost crust can be explained by fluid flow in a network of cracks in brittle rock. Increasing Qμ with depth to 10-15 km can be explained by the closing of those cracks due to pressure and their enhanced healing with increasing temperature. Plastic flow at greater depths may contribute further to the dissipation of cracks and to further increases in Qμ. Decreasing Qμ values at greater depths can be explained as being the result of increasing temperature, increasing content of partial melt, enhanced dislocation motion or some combination of these effects.

Attenuated leaky Rayleigh waves

The attenuation of leaky Rayleigh waves due to viscous damping in a boundary layer at the interface of an elastic solid half‐space and a fluid half‐space is studied by matched asymptotic method. Viscosity of the fluid is considered unimportant except in a thin boundary layer at the interface. By keeping the leading order effect, shown by the inverse of square root of a Reynolds number based on the shear velocity of the solid substrate, a new characteristic equation is obtained. One of the numerically obtained solutions gives the leaky Rayleigh wave speed and the attenuation coefficient due to both radiation into fluid and viscous damping of the boundary layer. It is shown that the viscous attenuation in the boundary layer may be as important as that due to radiation into the fluid half‐space for some fluid–substrate combinations. These results may be used to improve our interpretation of experimental results of acoustic signature of materials. Extension of the analysis to a fluid layer instead of a half‐space will be discussed. [Work supported by the Hunt Fellowship.]

Attenuated leaky Rayleigh waves

The propagation of leaky Rayleigh waves under the influence of viscous damping and heat conduction in boundary layers is studied using the matched asymptotic method. Viscosity of the fluid is considered unimportant except in a thin viscous boundary layer at the interface. A new characteristic equation is obtained in which the effect of boundary layer is shown by terms associated with R−1/2=(ων)1/2/ct, where R is the Reynolds number, ω is the frequency, ν is the kinematic viscosity of the fluid, and ct is the shear velocity of the solid substrate. One of the numerically obtained solutions gives the leaky Rayleigh wave speed and the attenuation coefficient. It is shown that, together with radiation, viscosity and heat conduction in the boundary layer also affect the attenuation of the leaky Rayleigh waves. Furthermore, it is shown that, because of the effect of the viscous boundary layer, the attenuated leaky Rayleigh wave speed can be smaller than the Rayleigh wave speed at the interface of a vacuum and a solid substrate. A critical Reynolds number of about 2500 is found beyond which a viscous boundary layer stops influencing leaky Rayleigh wave propagation. Finally, a new wave mode sustained by the viscous boundary layer alone is found in the limit of a small fluid–solid density ratio. This mode exists for appropriate frequency and layer thickness combinations. For air, the corresponding propagation speed is shown to be higher than the sound speed and the corresponding attenuation is significant. These results may be used to improve our interpretation of acoustic signature of materials.

Constraining Upper Mantle Anelasticity Using Surface Wave Amplitude Anomalies

SUMMARY We present an iterative method to constrain lateral variations in surface wave attenuation using long-period surface wave amplitude anomalies. the method acts to isolate the anelastic signal from elastic focusing effects, yielding largely unbiased estimates of lateral variations in the inverse seismic quality factor, q(ω) =Q=−1(ω) of the surface wave. In the zeroth iteration, linearized ray theory motivates the construction of a reduced datum, using measurements from four consecutive surface wave orbits, which is insensitive to elastic heterogeneity, an operation which requires no a priori knowledge of elastic structure. Synthetic experiments using both ray theoretic formalisms and normal-mode calculations reveal that significant levels of elastic bias remain in the reduced data due to deviations from linearized ray theory. In further efforts to eliminate elastic bias, the remaining elastic signal in each reduced datum is predicted and subtracted using accurate forward theory and existing aspherical elastic mantle models. This operation is the first iteration of a non-linear inversion in which the data at each iteration are the residuals between the observed anomalies and the anomalies predicted for a fixed phase velocity model and updated attenuation model. The zeroth and first iterations are performed with 1610 vertical and 790 longitudinal component seismograms from 144 events. Heterogeneity maps of Rayleigh wave attenuation δq(ω, θ, φ) are retrieved for the even degrees 2, 4 and 6 of a spherical harmonic expansion in the period range of 150–300s (oS25 - oS60)-These surface wave attenuation maps are analogous to elastic phase velocity in their radial averaging of, and linear relationship to, intrinsic heterogeneity and are inverted for upper mantle anelastic structure. Under the physically plausible assumption that intrinsic elastic and anelastic structure are correlated at every depth, the surface wave attenuation maps are well explained by a source region of anelastic heterogeneity that is radially localized in the shallow mantle (100-300 km) in a region we infer to be near the solidus temperature.

Attenuation of Multiphase Surface Waves in the Basin and Range Province Part II: The Fundamental Mode

Abstract In order to investigate the large errors which sometimes characterize fundamental-mode attenuation coefficient determinations, we have made many such determinations in the Basin and Range province and have plotted particle motion for the observed three-component seismograms. Rayleigh wave attenuation coefficient values determined for four two-station paths across the Basin and Range province fluctuate between about −2.0 × 10−3km−1 and +3.0 × 10−3km−1 at periods between 6 and 33 s. Partide motion plots indicate that many of those determinations are contaminated by arrivals from non-great circle paths and from waves generated at heterogeneities along the path, factors which lead to systematic errors in the measured attenuation coefficient values. Attenuation coefficient determinations for the path MNV to ELK, which is within 20° of being normal to the structural trends of the Sierra Nevada and Great Valley, are, however, relatively free from such contamination. Mean values for that path decrease rapidly with period from about 3.0 × 10−3 to about 0.7 × 10−3km−1 between 6 and 10 s and then decrease slowly to about 0.3 × 10−3km−1 at 33 s. Standard deviations range between 0.2 × 10−3 and 0.3 × 10−3km−1 for most of the period range, but increase to about 0.4 × 10−3 at periods between 6 and 8 s. These results indicate that careful screening, based upon criteria such as three-dimensional particle motion, are necessary to obtain surface wave attenuation data of sufficient quality to use for inverting for crustal anelasticity in complex regions.

Relationship of microseisms and ocean wave climatology.

Ocean waves have long been recognized as the source of sound in the ocean in the frequency band from 0.05 to 5 Hz. Ocean surface waves from nearly opposing directions interact to excite an elastic wave of much greater phase velocity. Necessarily, the climatology of microseisms is directly related to the climatology of ocean waves. However, the microseism energy propagates as free modes (Rayleigh waves) of the elastic wave waveguide set up by the seafloor and the steep gradient in elastic wave velocities below the seafloor. The propagation of elastic waves within the waveguide is frequency and model dependent. The modes propagate great distances which act to average the ocean wave climate over a large area. The size of this area is frequency dependent and is determined by the e-folding distance associated with attenuation of Rayleigh waves across the ocean. Data from arrays of seismic and pressure instruments in both the Atlantic and the Pacific will be compared to modeling results. The goal is to predict microseism climatology from ocean wave climatology. [Work supported by ONR.]

Upper mantle anelasticity and tectonic evolution of the western United States from surface wave attenuation

Rayleigh wave phase and group velocities and attenuation coefficients in the period range 18 to 120 s have been determined for three regions along nine paths across the western United States using a two‐station technique. The attenuation coefficients were found to increase from east to west between the Rocky Mountains and the Pacific coast. Rayleigh wave group and phase velocities were inverted, using a differential procedure, to obtain shear wave velocity models for three regions. These velocity models were then used in an inversion process where Qβ−1 as a function of depth was obtained from observations of Rayleigh wave attenuation. The inversion results show that Qβ values in the upper mantle of the western United States are lowest for the coastal regions and westernmost Basin and Range and highest for the Rocky Mountains and western Great Plains. Intermediate Qβ values appear to occur in the upper mantle beneath the Basin and Range province and the Columbia and Colorado plateaus, although uncertainties in the data prevent a clear separation between that region and coastal regions. Low values of Qβ occur in the upper crust, higher values in the lower crust, and highest values in the uppermost 20 km of the mantle of all these regions. These overlie an upper mantle low‐Q zone in which Qβ values decrease from east to west, lowest values (15–20) being similar to those observed above descending slabs in the western Pacific. The regional pattern of upper mantle shear wave Q values is similar to that observed for upper crustal shear wave Q values inferred from surface wave studies and for Lg coda Q values. The patterns of upper crustal and upper mantle Q variations correlate with the temporal sequence of tectonic and magmatic activity in the western United States, lowest Q values in both depth ranges occurring where tectonic activity has been most recent. Partial melting and/or enhanced dislocation motion in the mantle and variations in the volume of interstitial hydrothermal fluids in cracks in the upper crust may both be ultimately due to processes which occurred during plate consumption and interaction near the western margin of the United States.

Anelasticity of the crust and upper mantle beneath north and central India from the inversion of observed Love and Rayleigh wave attenuation data

The fundamental mode Love and Rayleigh waves generated by earthquakes occurring in Kashmir, Nepal Himalaya, northeast India and Burma and recorded at Hyderabad, New Delhi and Kodaikanal seismic stations are analysed. Love and Rayleigh wave attenuation coefficients are obtained at time periods of 15–100 seconds, using the spectral amplitude of these waves for 23 different paths along northern (across Burma to New Delhi) and central (across Kashmir, Nepal Himalaya and northeast India to Hyderabad and Kodaikanal) India. Love wave attenuation coefficients are found to vary from 0.0003 to 0.0022 km−1 for northern India and 0.00003 km−1 to 0.00016 km−1 for central India. Similarly, Rayleigh wave attenuation coefficients vary from 0.0002 km−1 to 0.0016 km−1 for northern India and 0.00001 km−1 to 0.0009 km−1 for central India. Backus and Gilbert inversion theory is applied to these surface wave attenuation data to obtainQβ−1 models for the crust and uppermost mantle beneath northern and central India. Inversion of Love and Rayleigh wave attenuation data shows a highly attenuating zone centred at a depth of 20–80 km with lowQ for northern India. Similarly, inversion of Love and Rayleigh wave attenuation data shows a high attenuation zone below a depth of 100 km. The inferred lowQ value at mid-crustal depth (high attenuating zone) in the model for northern India can be by underthrusting of the Indian plate beneath the Eurasian plate which has caused a low velocity zone at this shallow depth. The gradual increase ofQβ−1 from shallow to deeper depth shows that the lithosphere-asthenosphere boundary is not sharply defined beneath central India, but rather it represents a gradual transformation, which starts beneath the uppermost mantle. The lithospheric thickness is 100 km beneath central India and below that the asthenosphere shows higher attenuation, a factor of about two greater than that in the lithosphere. The very lowQ can be explained by changes in the chemical constitution taking place in the uppermost mantle.

Preliminary shear Q structure in the Mediterranean Sea from Rayleigh wave observations

Fundamental-mode Rayleigh wave attenuation coefficients have been obtained for the Mediterranean Sea using the two-station method applied to seismograph stations located in the coastal regions of Spain and Israel. The average attenuation coefficients vary between 7.36 10 −4 km −1, at a 16 s period, to 0.76 10 −4 km −1 at a 70 s period. The associated Rayleigh wave anelastic factors range from 42 to 157. The above results indicate a relatively highly attenuating region. Inversion methods applied to the determined Rayleigh wave attenuation coefficients indicate that a strong and well-developped shear Q structure seems to be located under the Mediterranean Sea.

Q-structure beneath the north and central Indian Ocean from the inversion of observed Love and Rayleigh wave attenuation data

The fundamental-mode Love and Rayleigh waves generated by 57 earthquakes which occurred in the north and central Indian Ocean (extending to 40°S) and recorded at Indian seismograph and other WWSSN stations such as HOW, SHL, VIS, MDR, HYB, KOD, CHG, TRD, POO, BOM, GOA, NDI, NIL and QUE are analysed. Love and Rayleigh wave attenuation coefficients are estimated at periods of 15–100 s using the spectral amplitude of these waves for 98 different paths across the Bay of Bengal Fan, the Arabian Fan, and the north and central Indian Ocean. The large standard deviations observed in the surface wave attenuation coefficients may be a result of regional variation of the attenuative properties of the crust and upper mantle beneath these regions. Love wave attenuation coefficients are found to vary from 0.000 03 to 0.000 45 km −1 for the Bay of Bengal Fan; from 0.000 03 to 0.000 85 km −1 for the Arabian Fan; and from 0.000 03 to 0.000 35 km −1 for the north and central Indian Ocean. Similarly, Rayleigh wave attenuation coefficients vary from 0.000 03 to 0.0004 km −1 for the Bay of Bengal Fan; from 0.000 06 to 0.0007 km −1 for the Arabian Fan; and from 0.000 03 to 0.0007 km −1 for the north and central Indian Ocean. Backus and Gilbert inversion theory is applied to these surface wave attenuation data to obtain average Q −1 models for the crust and upper mantle beneath the Bay of Bengal, the Arabian Fan, and the north and central Indian Ocean. Inversion of Love and Rayleigh wave attenuation data shows a high-attenuation zone centred at a depth of > 120 km ( Q β ≈ 125) for the Bay of Bengal Fan. Similarly, a high-attenuation zone ( Q β ≈ 40–70) occurs at a depth of 60–160 km for the Arabian Fan at 100–160 km ( Q β ≈ 115) for the Indian Ocean off Ninetyeast Ridge, and at 80–160 km ( Q β ≈ 80) for the Indian Ocean across the Ninetyeast Ridge. The Q β −1 models show a lithosphere thickness of 120 km beneath the Bay of Bengal Fan. Similarly, lithosphere thickness of 70, 100 and 80 km is estimated beneath the Arabian Fan, and the Indian Ocean off Ninetyeast Ridge and across Ninetyeast Ridge, respectively. The base of the lithosphere is identified as the depth at which there is a significant increase in the Q β −1 value, which attains its maximum value in the asthenosphere. The thinning of Indian lithosphere beneath the Arabian Fan suggests high temperature below Moho depth (60 km from surface) which has caused a high-attenuation zone at this shallow depth.

BLOCKING SURFACE WAVES BY A CUT PHYSICAL SEISMIC MODEL RESULTS1

ABSTRACTHigh resolution seismic reflection exploration for minerals places severe demands on field practice so as to maximize the signal‐to‐noise bandwidth. In particular, all horizontally propagating coherent noise, especially ground roll, must be attenuated.The blocking effect of a trench between source and receiver has been investigated by means of two‐dimensional physical seismic model experiments. Rectangular, circular and wedge‐shaped saw‐cuts of various dimensions were studied. The results show that thin rectangular cuts of depth equal to one‐quarter of the Rayleigh wave noise wavelength produce a 12 dB or better improvement in the signal‐to‐noise ratio. Rayleigh wave attenuation is greater than 30 dB at a cut depth of one wavelength. In the field applications envisaged, this corresponds to trenches up to a few metres deep. The trenches should be filled with foam or loose sand to dampen out mode conversion and diffraction noise. There are obvious practical difficulties of implementing such a technique in routine CMP operations.The technical effectiveness of the saw‐cut is illustrated by imaging a deeply‐buried small hole (diffractor) in an aluminium plate. Without the saw‐cut between source and receiver, the seismic record is dominated by Rayleigh wave noise, masking P‐wave arrivals from the target diffractor. However, with a saw‐cut of depth three‐quarters of a Rayleigh wave wavelength, the improvement is dramatic, making it easy to detect and identify the hole. When scaled to the field situation, this is equivalent to imaging a 6 m tunnel at a depth of 400 m, using a surface trench of depth 2 m to block ground roll.

Scattering of long-period Rayleigh waves in Western North America and the interpretation of codaQmeasurements

AbstractThe codas of long-period Rayleigh waves recorded at WWSSN and Canadian network stations in Western North America from eight underground explosions at NTS are examined in an effort to separate scattering and anelastic attenuation effects. Coda behavior of 0.1 and 0.2 hz Rayleigh waves follows coda characteristics seen in studies of short-period S waves. Coda decay rate is seen to be a stable observation over most stations in Western North America and is consistent with the hypothesis that backscattered surface waves from heterogeneities contained within the western half of the continent form the Rayleigh wave coda. The basic data observables of coda level and decay are interpreted using several plausible models. The single scattering model yields a coda Q consistent with previously determined Rayleigh anelastic attenuation coefficients. Separation of anelastic and scattering Q is possible using an energy flux model and shows that scattering Q is one to two orders of magnitude higher than anelastic Q. However, an energy flux model that incorporates a layer of scatterers over a homogeneous half-space shows that all Rayleigh-wave attenuation can be explained purely by scattering effects which include Rayleigh- to body-wave conversion. Coda can be fit equally well by these mutually incompatible models. It is not likely that the mechanisms of scattering or anelastic attenuation can be addressed by coda observations of a single homogeneous data set.

Frequency dependence of crustalQ ? in stable and tectonically active regions

Fundamental-mode Rayleigh wave attenuation data for stable and tectonically active regions of North America, South America, and India are inverted to obtain several frequency-independent and frequency-dependentQβ models. Because of trade-offs between the effect of depth distribution and frequency-dependence ofQβ on surface wave attenuation there are many diverse models which will satisfy the fundamental-mode data. Higher-mode data, such as 1-Hz Lg can, however, constrain the range of possible models, at least in the upper crust. By using synthetic Lg seismograms to compute expected Lg attenuation coefficients for various models we obtained frequency-dependentQβ models for three stable and three tectonically active regions, after making assumptions concerning the nature of the variation ofQβ with frequency.

Correlation between high-frequency Rayleigh wave attenuation and dc magnetoresistance in nickel thin films

We present experimental data showing a correlation between the magnetic field dependence of the attenuation of 601.4-MHz Rayleigh-mode surface acoustic wave propagating through evaporated thin films of Ni and the dc magnetoresistance of these films. This correlation provides (1) a method for characterizing the magnetoelastic coupling between the Rayleigh waves and the films’ magnetic moment and (2) insight into the magnetic domain structure and anisotropy dispersion of these films which typically have uniaxial magnetic anisotropy. Upon application of relatively modest dc magnetic fields (&amp;lt;80 Oe) in the film plane both the variation in surface wave attenuation (70 dB/cm) and magnetoresistance (≂1%) can be quite large.

Magnetic effect on the hydrogen entry in iron detected by Rayleigh wave attenuation

Magnetic effect on the hydrogen entry in iron detected by Rayleigh wave attenuation