Title :
Relaxation behavior of ultrasonic attenuation in YBa2Cu 3O7
Author :
Sun, K.J. ; Winfree, W.P. ; Xu, M.F. ; Sarma, Bimal K. ; Levy, M. ; Caton, R. ; Selim, R.
Author_Institution :
Dept. of Phys., Coll. of William & Mary, Williamsburg, VA, USA
fDate :
3/1/1989 12:00:00 AM
Abstract :
It is shown that temperature-dependence ultrasonic attenuation data of YBa2Cu3O7 at various frequencies exhibit anomalies at temperatures close to Tc . These attenuation maxima are found to be the result of a relaxation mechanism added on top of an unusual attenuation background. It is proposed that the grain boundary motions induced by the structural distortion and the propagation of sound waves enhances the energy dissipation around Tc. Whether this structural distortion is the consequence of the onset of a superconducting state remains undetermined. It is also possible that either a tunneling effect of the acoustoelectric effect contributes to sound energy dissipation. The temperature dependence of ultrasonic velocity shows a softening around Tc which may be an intrinsic property of high-temperature superconductors
Keywords :
acoustoelectric effects; barium compounds; grain boundaries; high-temperature superconductors; superconducting transition temperature; superconductive tunnelling; ultrasonic absorption; ultrasonic velocity; yttrium compounds; YBa2Cu3O7; acoustoelectric effect; attenuation maxima; energy dissipation; grain boundary motions; high temperature superconductors; relaxation mechanism; structural distortion; transition temperature; tunneling effect; ultrasonic attenuation; ultrasonic velocity; Acoustic propagation; Acoustoelectric effects; Attenuation; Energy dissipation; Frequency; Grain boundaries; High temperature superconductors; Softening; Temperature dependence; Tunneling;
Journal_Title :
Magnetics, IEEE Transactions on
