| | |
Summary: 3594 IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 13, NO. 2, JUNE 2003
Study of Local Nonlinear Properties Using a
Near-Field Microwave Microscope
Sheng-Chiang Lee and Steven M. Anlage, Member, IEEE
Abstract--We have developed a near-field microwave micro-
scope to locally apply microwave frequency currents and fields to
superconductors, and dielectric substrates, and measure the locally
generated 2nd and 3rd harmonic responses. We measure the local
nonlinear response of a Tl2Ba2CaCu2O film grown on an MgO
substrate, and observe a large response due to the enhanced cur-
rent density near the edge. We also study the local nonlinear re-
sponse of a YBa2Cu3O7 thin film grown on a bi-crystal SrTiO3
(STO) substrate, and spatially identify the grain boundary through
higher harmonic measurements. The spatial resolution is deter-
mined by the magnetic loop probe size. A scaling current density
NL is extracted to quantify the magnitude of the nonlinearity of
the superconductor. Preliminary results on the nonlinear proper-
ties of some commonly used substrates, e.g., MgO and STO, have
also been obtained.
Index Terms--Harmonic generation, Josephson junctions,
|
