Summary: Doping dependent time-reversal symmetric nonlinearity
of YBa2Cu3O7Àd thin films
Sheng-Chiang Lee, Steven M. Anlage *
Center for Superconductivity Research, Physics Department, University of Maryland, College Park 20742-4111, USA
Abstract
We have measured the temperature dependent third harmonic response from a series of under-doped YBa2Cu3O7Àd
thin films to address the mechanism of nonlinearity in these samples. We find that the intrinsic Ginzburg­Landau
nonlinearity near Tc is doping dependent, with the sample becoming more nonlinear as it is under-doped. The results are
consistent with the doping dependence of the condensation energy of YBa2Cu3O7Àd.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Microwave; Nonlinear; Superconductor; Doping
1. Introduction
The well-known Ginzburg­Landau description of
superconductivity predicts an intrinsic third order non-
linearity of the superfluid response, which is enhanced
tremendously near Tc. Another well-known third-order
nonlinearity of interest in high-temperature supercon-
ductors (HTSC) occurs in the Andreev bound state
(ABS). To explore and provide an alternative means to
locally study these nonlinearities, we employ our near-

Source: Anlage, Steven - Center for Superconductivity Research & Department of Physics, University of Maryland at College Park

Collections: Materials Science