中国物理B ›› 1993, Vol. 2 ›› Issue (12): 937-946.doi: 10.1088/1004-423X/2/12/008

• • 上一篇    

INTERNAL FRICTION AND ULTRASONIC ATTENUATION RELATED TO CARRIERS IN HIGH Tc SUPERCONDUCTORS

曹国辉1, 赵忠贤2, 刘鹏2, 张进龙2, 司卫东2, 黄以能3, 王业宁3, 陈沙鸥3, 周海龙3, 张清明3, 沈惠敏3, 杨震3   

  1. (1)Department of Materials Physics, Beijing University of Science and Technology, Beijing 100083, China; (2)National Laboratory for Superconductivity, Institute of Physics, Academia Sinica, Beijing 100080, China; (3)National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210008, China
  • 收稿日期:1993-03-15 出版日期:1993-12-20 发布日期:1993-12-20
  • 基金资助:
    Project supported by the National Center for Research and Development on Superconductivity of China.

INTERNAL FRICTION AND ULTRASONIC ATTENUATION RELATED TO CARRIERS IN HIGH Tc SUPERCONDUCTORS

HUANG YI-NENG (黄以能)a, WANG YE-NING (王业宁)a, CHEN SHA-OU (陈沙鸥)a, ZHOU HAI-LONG (周海龙)a, ZHANG QING-MING (张清明)a, SHEN HUI-MIN (沈惠敏)a, YANG ZHEN (杨震)a, ZHAO ZHONG-XIAN (赵忠贤)b, LIU PENG (刘鹏)b, ZHANG JIN-LONG (张进龙)b, SI WEI-DONG (司卫东)b, CAO GUO-HUI (曹国辉)c   

  1. a National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210008, China; b National Laboratory for Superconductivity, Institute of Physics, Academia Sinica, Beijing 100080, China; c Department of Materials Physics, Beijing University of Science and Technology, Beijing 100083, China
  • Received:1993-03-15 Online:1993-12-20 Published:1993-12-20
  • Supported by:
    Project supported by the National Center for Research and Development on Superconductivity of China.

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摘要： For both BiSrCaCuO and TlBaCaCuO samples, internal frictions (Q-1) in the kHz range reveal a plateau (Q-1p) above Tc and a rapid drop below Tc with the turning points located just at Tc for various samples with different Tc. This anomaly cannot be observed in non-superconducting samples. The ultrasonic attenuation (α) in TlBaCaCuO displays similar results to the internal friction. Moreover, it is discovered that the Q-1p is nearly proportional to the carrier density for Y(Pr)BaCuO and Gd(Pr)BaCuO with different Pr contents. These results show that the drop of Q-1 and a below Tc is closely related to superconducting condensation. The Q-1p and αp can be explained using coupling-model of carriers with local dynamic distortion because high Tc superconductors are strong-correlation systems. Furthermore, by taking account of the smearing of superconducting gap structure resulting from the recombination of quasi-particles and by modifying the BCS relative jump rate as S(E, E', Γ) = Re{1-Δ2/[(E-iΓ)(E'-iΓ)]}, the calculated results of internal friction and ultrasonic attenuation below Tc are in good agreement with the experimental data. The superconducting gap Δ and the damping rate Γ for both BiSrCaCuO and TlBaCaCuO have also been obtained, they are in accordance with those got by tunneling spectrum and NMR methods, etc.

Abstract: For both BiSrCaCuO and TlBaCaCuO samples, internal frictions (Q-1) in the kHz range reveal a plateau (Q-1p) above Tc and a rapid drop below Tc with the turning points located just at Tc for various samples with different Tc. This anomaly cannot be observed in non-superconducting samples. The ultrasonic attenuation ($\alpha$) in TlBaCaCuO displays similar results to the internal friction. Moreover, it is discovered that the Q-1p is nearly proportional to the carrier density for Y(Pr)BaCuO and Gd(Pr)BaCuO with different Pr contents. These results show that the drop of Q-1 and a below Tc is closely related to superconducting condensation. The Q-1p and $\alpha$p can be explained using coupling-model of carriers with local dynamic distortion because high Tc superconductors are strong-correlation systems. Furthermore, by taking account of the smearing of superconducting gap structure resulting from the recombination of quasi-particles and by modifying the BCS relative jump rate as S(E, E', $\varGamma$) = Re{1-$\Delta$2/[(E-i$\varGamma$)(E'-i$\varGamma$)]}, the calculated results of internal friction and ultrasonic attenuation below Tc are in good agreement with the experimental data. The superconducting gap $\Delta$ and the damping rate $\varGamma$ for both BiSrCaCuO and TlBaCaCuO have also been obtained, they are in accordance with those got by tunneling spectrum and NMR methods, etc.

中图分类号:  (Mechanical and acoustical properties, elasticity, and ultrasonic Attenuation)

  • 74.25.Ld
74.25.Jb (Electronic structure (photoemission, etc.)) 74.20.Fg (BCS theory and its development) 62.40.+i (Anelasticity, internal friction, stress relaxation, and mechanical resonances) 74.50.+r (Tunneling phenomena; Josephson effects)