Use of Kramers-Kronig relations to extract the conductivity of high-[ital T][sub [ital c]] superconductors from optical data

Journal Article · Sat May 01 00:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.47.12308· OSTI ID:6608642

Miller, D; Richards, P L ^[1]

---

1. Department of Physics, University of California, and Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

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 [similar to]300 cm[sup [minus]1] the reflectivities of materials such as YBa[sub 2]Cu[sub 3]O[sub 7] 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 YBa[sub 2]Cu[sub 3]O[sub 7] 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 [ital a]-[ital b] plane conductivity. However, below 450 cm[sup [minus]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.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6608642
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 47:18; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
HIGH-TC SUPERCONDUCTORS
MEASURING METHODS
AC LOSSES
BOLOMETERS
ELECTRIC CONDUCTIVITY
FAR INFRARED RADIATION
FILMS
FREQUENCY DEPENDENCE
KRAMERS-KRONIG CORRELATION
MICROWAVE RADIATION
REFLECTIVITY
CORRELATIONS
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ENERGY LOSSES
INFRARED RADIATION
LOSSES
MEASURING INSTRUMENTS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
SUPERCONDUCTORS
SURFACE PROPERTIES
665411* - Basic Superconductivity Studies- (1992-)
360204 - Ceramics
Cermets
& Refractories- Physical Properties