Microwave conductivity of patterned YBa/sub 2/Cu/sub 3/O/sub 7/ thin films

Author

Porch, A. ; Powell, J.R. ; Lancaster, M.J. ; Edwards, J.A. ; Humphreys, R.G.

Author_Institution

Sch. of Electron. Eng., Birmingham Univ., UK

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

1987

Lastpage

1990

Abstract

We have used coplanar resonators to provide a sensitive measure of the ab-plane microwave complex conductivity /spl sigma/=/spl sigma//sub 1/-i/spl sigma//sub 2/ at 8 and 16 GHz of high quality, patterned thin films of YBa/sub 2/Cu/sub 3/O/sub 7-/spl sigma// on MgO substrates. No BCS coherence effects were observed in /spl sigma/1(T) below T/sub c/. Instead, we observe a broad peak centred between 40 and 50 K, which was present in all of the samples. The T dependence of the magnetic penetration depth /spl lambda/(T)=(/spl omega//spl mu//sub 0//spl sigma//sub 2/(T))/sup -1/2/ also differed from that expected for a BCS superconductor in the London limit. This difference is most noticeable at low T, where instead of the usual exponential T dependence, we observe a term in T/sup 2/ for every sample. We discuss briefly the effects of sample oxygenation on these results.<>

Keywords

barium compounds; high-frequency effects; high-temperature superconductors; penetration depth (superconductivity); superconducting resonators; superconducting thin films; yttrium compounds; 16 GHz; 40 to 50 K; 8 GHz; London limit; MgO; MgO substrates; YBa/sub 2/Cu/sub 3/O/sub 7-/spl sigma//; YBa/sub 2/Cu/sub 3/O/sub 7/; ab-plane microwave complex conductivity; broad peak; coplanar resonators; high quality; high temperature superconductors; magnetic penetration depth; patterned YBa/sub 2/Cu/sub 3/O/sub 7/ thin films; sample oxygenation; temperature dependence; Annealing; Argon; Conductivity measurement; Electromagnetic heating; Substrates; Superconducting magnets; Superconducting materials; Surface impedance; Transistors; Yttrium barium copper oxide;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.402975

Filename

402975