Non-linear microwave surface impedance of epitaxial HTS thin films in low DC magnetic fields

A. P. Kharel, K. H. Soon, J. R. Powell, A. Porch, M. J. Lancaster, A. V. Velichko, R. G. Humphreys

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


We have carried out non-linear microwave (8 GHz) surface impedance measurements of three YBaCuO thin films in dc magnetic fields Hdc (parallel to c axis) up to 12 mT using a coplanar resonator technique. In zero dc field the three films, deposited by the same method, show a spread of low-power residual surface resistance, Rrcs and penetration depth, A (T = 15 K) within a factor of 1.9. However, they exhibit dramatically different microwave field, Hr; dependences of the surface resistance, Rs, but universal Xs(Hr/) dependence. Application of a dc field was found to affect not only absolute values of R, and Xs, but the functional dependences R,(HTf] and X,(Hr/) as well. For some of the samples the dc field was found to decrease Ra below its zero-field low-power value.

Original languageEnglish
Pages (from-to)2121-2124
Number of pages4
JournalIEEE Transactions on Applied Superconductivity
Issue number2 PART 2
Publication statusPublished - 1 Dec 1999

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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