USE OF KRAMERS-KRONIG RELATIONS TO EXTRACT THE CONDUCTIVITY OF HIGH-TC SUPERCONDUCTORS FROM OPTICAL-DATA

被引:19
作者
MILLER, D [1 ]
RICHARDS, PL [1 ]
机构
[1] LAWRENCE BERKELEY LAB,DIV MAT SCI,BERKELEY,CA 94720
来源
PHYSICAL REVIEW B | 1993年 / 47卷 / 18期
关键词
D O I
10.1103/PhysRevB.47.12308
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
In principle the conductivity of the cuprate superconductors can be obtained from reflectivity measurements using the Kramers-Kronig-transform technique. However, at low temperatures and for frequencies below approximately 300 cm-1 the reflectivities of materials such as YBa2Cu3O7 are close to unity. Uncertainty in the precise signal level corresponding to unity reflectivity and a lack of knowledge of the reflectivity below the lowest measured frequency cause this method to become unreliable. To address this problem we have used a bolometric technique and a resonant technique to obtain accurate submillimeter and microwave data for the residual losses in epitaxial thin films of YBa2Cu3O7 at low temperatures. The Kramers-Kronig analysis of our data is in good agreement with results from fitting our data to simple weakly coupled grain and two-fluid models for the a-b plane conductivity. However, below 450 cm-1 it is in disagreement with some published results of other workers obtained from Kramers-Kronig analysis of reflectivity data. To understand this discrepancy we analyze how the conductivity determined by the Kramers-Kronig-transform technique depends on some commonly used low-frequency extrapolations of reflectivity data,
引用
收藏
页码:12308 / 12311
页数:4
相关论文
共 21 条
[21]   INFRARED OBSERVATION OF 2-FLUID SUPERCONDUCTIVITY IN YBA2CU3O7-X [J].
VANDERMAREL, D ;
BAUER, M ;
BRANDT, EH ;
HABERMEIER, HU ;
HEITMANN, D ;
KONIG, W ;
WITTLIN, A .
PHYSICAL REVIEW B, 1991, 43 (10) :8606-8609