• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Nov 1988

Volume 84, Issue S1, pp. S2-S224

Return to All Sections
back to top
RSS Feeds
back to top Session JJ. Physical Acoustics IV: Role of Acoustics in High‐Temperature Superconductors
Invited Papers
FREE

Anomalous ultrasound propagation in high‐Tc superconductors (A)

S. Bhattacharya

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S108-S109 (1988); (2 pages)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
Propagation of longitudinal and transverse ultrasound in high‐Tc superconductors reveals unusual behavior at and below Tc. The superconducting order parameter is found to possess a large coupling to some volume‐preserving shear distortions. Unlike in conventional superconductors, the behavior below Tc, is inconsistent with a condensation of the carriers alone. The elastic modulus behavior below Tc is reminiscent of charge density wave/spin density wave transitions. The attenuation below Tc correlates with thermal transport and is related to either a strong phonon‐phonon interaction or the Zener effect of intergranular heat transport in polycrystalline systems. Several anomalies in both the velocity and the damping are observed between Tc,. and room temperature, indicating the presence of other phase transitions of yet unknown origins. Magnetic field dependence of sound velocity shows fluctuation effects above Tc and a large stiffening below Tc probably related to an unusual flux‐lattice dynamics. Implications of these results on the nature of superconductivity will be discussed.
FREE

Flux lattices in the high‐Tc superconductors (A)

D. J. Bishop

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S109-S109 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
Two types of experiments that provide information about the statics and dynamics of flux lattices in YBa2Cu3O7 will be discussed. The first are magnetic decoration experiments in which the flux lines are decorated with magnetic particles. From these experiments, it has been learned that the flux lattice is triangular with the normal value for the flux quantum. In ultrasound and high‐Q mechanical oscillator experiments flux lattice melting has been examined. These experiments show that the flux lattice melts well below Hc2 into a vortex liquid state. These results suggest that the vortex solid and its melting is essentially two dimensional in character.
FREE

Acoustic studies of single‐crystal high‐temperature superconductors (A)

Brage Golding, W. H. Haemmerle, and L. F. Schneemeyer

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S109-S109 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
The acoustic properties of single crystals of the high‐temperature superconductor YBa2Cu3O7 have been measured at temperatures between 0.1 and 300 K for frequencies near 103 and 109 Hz. In the GHz regime, longitudinal modes have been studied for propagation directions parallel and perpendicular to the c axis. At Tc, there is a discontinuity in the sound velocities and their temperature derivatives from which the anisotropic strain dependences of Tc are obtained. In the kHz regime, resonant excitation of flexural modes in thin reeds of YBa2Cu3O7 crystals has permitted precise measurement of acoustic damping and dispersion. The temperature‐dependent damping is characterized by at least five features associated with the relaxation of defects. At temperatures below 1 K, the velocity of sound is consistent with the presence of a broad “glasslike” distribution of tunneling modes.
FREE

Optical phonons and electron‐phonon interactions in high‐Tc materials as probed by Raman scattering (A)

M. V. Klein, S. L. Cooper, F. Slakey, B. G. Pazol, J. P. Rice, and D. M. Ginsberg

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S109-S109 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
Raman scattering has played two roles in high Tc superconductivity studies: characterization and fundamental physical properties. After one has separated intrinsic spectra from those due to impurity phases, the physical properties of the intrinsic superconducting material may then be studied. In single crystals of YBa2Cu3O7−δ, the most interesting Raman‐active mode is one at 330 cm−1 due to O atoms in the “planes.” This mode has nearly pure B1g tetragonal symmetry, even in the orthorhombic phase, and it shows strong softening below Tc. In detail, its Raman spectra reveal a Fano antiresonance with a continuum [Cooper et al., Phys. Rev. B 37, 5920–5923 (1988)] of the same symmetry. An Ag mode at 118 cm−1 assigned primarily to Ba vibrations shows an even stronger antiresonance, but little softening. The continuum responsible for its antiresonance has Ag symmetry and a somewhat different shape from that of the B1g continuum, but both Raman continua extend all the way to zero Raman frequency shift, implying linear low‐frequency response. For T≪Tc, the linear response is still present with five times reduced intensity, implying some form of gaplessness to the superconducting state. Efforts to rule out spurious surface effects will be described, and comparisons with results on materials such as Bi2Sr2Ca1Cu2O8 + δ will be made. [Work supported by NSF under DMR 8715103 and DMR 8612860.]
FREE

Ultrasonic studies of the roles of the electron‐phonon interaction in high‐Tc superconductors (A)

Shoichi Mase and Yuuji Horie

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S110-S110 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
The role of the electron‐phonon interaction in high‐Tc superconductors MBa2Cu3O7 (M = Y, Nd, and others), (La1−xSrx)2CuO4, and BaPb1−xBixO3 were studied by acoustic means. At scores of MHz, only BaPb1−xBixO3 showed an appreciable electronic contribution to the sound attenuation, suggesting the largeness of the electron‐phonon interaction. For higher Tc samples, no evidence of the electronic contribution was found, as can be predicted by the absence of the isotope effect in YBa2Cu3O7. Structural instability was, however, investigated for some samples, and the energies of optical modes were estimated. Based on these experimental results and others, the phonon dispersion curves and the density of state curves D(ϵ) were calculated in agreement with inelastic neutron scattering data on D(ϵ). The calculated results show that the optical modes due to Cu‐O and OO bonds in YBa2Cu3O7 provide large contributions to the electron‐phonon interaction in view of the energy scale and symmetry properties of wavefunctions. There will be some discussion on what factors counterbalance these advantages. Using single crystals of YBa2Cu3O7 and NdBa2Cu3O7, measurements are being carried out to derive more accurate acoustic information.
FREE

Resonant ultrasound measurements in single crystals of intrinsic and superconducting copper‐oxygen plane compounds (A)

Albert Migliori, Stuart E. Brown, Zachary Fisk, Eric T. Ahrens, J. D. Maynard, and J. H. Mather

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S110-S110 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
Resonant ultrasound measurements in very pure single crystals of La2CuO4 have been made. The material was prepared such that its resistivity at 300 K is extremely high (170 Ω cm), and untwinned crystals of about 0.1×0.1×0.1 cm were used. Oxygen was then introduced, eventually leading to superconductivity. Here, data on the three longitudinal sound velocities and attenuations as a function of temperature for different oxygen dopings are presented and the effects of magnetic and superconducting interactions are discussed. All data were taken with a resonant ultrasound method developed by us in which the transducers are flexible and are less than 1% of the sample mass, minimizing transducer loading effects.
FREE

Ultrasonic studies of sintered YBa2Cu3O6.9 and La2CuO4 single crystals (A)

Yuichi Okuda

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S110-S110 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
Single‐phase sintered YBa2Cu3O6.9 exhibits no anomaly in the attenuation around Tc (90 K). On the other hand, its sound velocity shows an anomalous increase just below Tc. This may come from lattice hardening due to the condensation of holes. To clarify the relation between this anomaly and the superconductivity, measurement under 8 Tesla was performed. Exactly the same anomaly was observed at 90 K and nothing happened around 72 K, which is the critical temperature under 8 Tesla. The hardening may not be directly related to the superconductivity of this material. An ultrasonic study of a single crystal of La2CuO4 is being made to investigate its antiferromagnetic property, which may be a key in understanding the new superconductivity. A small peak in the attenuation at TN and a very small anomaly in the sound velocity were observed at 43 MHz. The result of a study on a single crystal of YBa2Cu3O6.9 will also be presented at the conference.
FREE

Anomalies in the elastic properties of the high‐temperature superconductors (A)

D. P. Almond, G. A. Saunders, E. F. Lambson, A. Al‐Kheffaji, and M. Cankartaran

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S110-S111 (1988); (2 pages)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
Measurements will be presented of the ultrasonic wave velocity and attenuation in high‐density polycrystalline samples of YBa2Cu3O7 at temperatures between 4.2 and 300 K. Both longitudinal and shear wave data were found to be characterized by thermal hysteresis and run‐to‐run variations. At temperatures below Tc, the hysteresis disappeared, the elastic constants increased, and the attenuation fell. The higher temperature measurements were affected by sample annealing and thermal history and exhibited recovery effects. The pressure dependence of the elastic constants was found to be very large and also to exhibit hysteresis effects. These phenomena are consistent with the suggestion that these ceramics are pseudoplastic solids in which the plasticity is attributed to the mobility of twin boundaries. Recent measurements of Bi‐Ca‐Sr‐Cu‐O superconductors will also be presented.
Contributed Papers
FREE

Ultrasonic studies of high‐Tc superconductors (A)

Yuuji Horie, Yuichiro Terashi, Hiroshi Fukuda, Masanori Hidaka, Takeshi Fukami, and Shoichi Mase

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S111-S111 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
High‐Tc oxide superconductors [MBa2Cu3O7 (M = Y and lanthanoids), (La1−xSrx)2CuO4, BaPb1−xBixO3, x < 0.35] and their related insulating oxides [MBa2Cu3O6, BaPb1−xBixO3, x > 0.35] were investigated by means of ultrasonic measurements. By using sound waves of f0 = 10 MHz, we observed several peaks in the curves of the attenuation coefficient α(T) versus the temperature T for the superconducting samples. These peaks can be attributed to sound energy dissipation accompanied by excitations in optical phonons. However, there was no obvious anomaly near Tc except for BaPb0.8Bi0.2O3 with f0∼30 MHz. The electronic contribution to α(T) was estimated to be very small in the Pippard mechanism of attenuation because of low electrical conductivity and a low f0. In order to increase f0, measurements with single‐crystal samples having smaller resistivity are in progress. On the other hand, in the insulating samples, there are several peaks in the α(T) versus the T curves that can be assigned to some structural modulation. This assignment is supported by these piezoelectric and capacitance measurements. On the basis of these experimental results, the phonon contributions to high‐Tc superconductivity are discussed.
FREE

Ultrasonic attenuation and velocity investigation of sinter‐forged superconducting YBa2Cu3O7 (A)

M. Levy, B. K. Sarma, M.‐F. Xu, S. Adenwalla, Z. Zhao, Q. Robinson, and J. B. Ketterson

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S111-S111 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
Sinter‐forged YBa2Cu3O7 exhibits rotational symmetry about the forging axis with the c axis of 80% of the crystallites aligned within 2° of the forging axis. Attenuation measurements as a function of temperature of longitudinal waves propagating perpendicular to the forging axis exhibit it three broad relative maxima at 70, 180, and 250 K. Attenuation measurements with either longitudinal or transverse waves propagating along the forging axis exhibit only one maximum at about 180 K. The absence of the other two maxima along this orientation indicates that they could be produced by interaction mechanisms that may be associated with the Cu‐O planes, while the 180‐K maximum may be produced by an isotropic interaction mechanism. Sound velocity measurements show the sinter‐forged material to be elastically anisotropic. The temperature dependence of the sound velocity shows distinct hysteresis curves that flatten out if the sample is not warmed above 250 K. Upon cooling, lattice softening is observed to start at temperatures much higher than Tc, and to stop below Tc. [Work supported by ONR at the University of Wisconsin−Milwaukee and by NSF at Northwestern University.]
FREE

Can you hear the elastic tensor? (A)

William M. Visscher

J. Acoust. Soc. Am. Volume 84, Issue S1, pp. S111-S111 (1988); (1 page)

Online Publication Date: 13 Aug 2005

Full Text: | Download PDF

Show Abstract
The measured response of an object of known size and shape composed of a homogeneous but anisotropic elastic material as a function of frequency of excitation is, in principle, enough to determine the linear elastic constants, 21 of them in the most general case. A method for computing the resonant frequencies is explained and illustrated for an object of simple geometry (a×b×c rectangular parallelepiped) with free or clamped faces of a material whose elastic modulus tensor reflects the symmetry of an orthorhombic lattice (nine independent constants). The method is a variant of MOOT [method of optimal truncation, see J. L. Opsal and W. M. Visscher, J. Appl. Phys. 58, 1102 (1985)], which is a boundary residual method developed to compute elastic wave scattering. The calculation was undertaken as a part of the analysis of measurements of ultrasonic response of single‐crystal, high‐temperature superconductor materials (reported elsewhere at this meeting). Results will be presented, and the practicality of this approach to determine unknown elastic constants will be discussed. [Work supported by USDOE.]
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close