A cryogenic microwave scanning near-field probe: Application to study of high-Tc superconductors

Abstract

An inexpensive and easy experiment to measure the electrical resistance of high-T c superconductors as a function of temperature Am.We report a vacuum cryogenic ͑80 KϽTϽ350 K͒, near-field microwave scanning system based on a 90 GHz transmitting/receiving resonant slit antenna with a capacitive measurement of the probe-sample separation. The probe allows local measurement of resistance as a function of temperature with the spatial resolution of 20-50 m. The mm-wave probe is integrated with the eddy-current probe which allows global measurement of resistance of conducting and superconducting samples. This integrated probe is used for local study of the superconducting transition in high-T c superconducting thin films. The sensitivity of our present mm-wave probe is sufficient for probing conductivity in the normal state and in the superconducting state close to T c however not yet sufficient for probing conductivity variations far below superconducting transition temperature.

Microwave studies of thin manganite films on SrTiO3 substrate

“…14, 18 We assume ͑i͒ a thin conducting film sample on the front side of a substrate, ͑ii͒ a perfectly conducting layer on the back side of the substrate, and ͑iii͒ a narrow microwave beam incident on the film, whereby the electric and magnetic fields are tangential to it ͑Fig. 14, 18 We assume ͑i͒ a thin conducting film sample on the front side of a substrate, ͑ii͒ a perfectly conducting layer on the back side of the substrate, and ͑iii͒ a narrow microwave beam incident on the film, whereby the electric and magnetic fields are tangential to it ͑Fig.…”

Detection of low-level dissipation and thermal instability in Y Ba2Cu3O7 − δmicrobridges using low temperature near-field scanning microwave microscopy

“…At temperatures above T c , however, the surface impedance has a weak temperature dependence which should account for the variations in S 11 in this temperature range. Previous works have shown the capability of NSMM to correlate changes in the resonator's properties with the transition to superconductivity when the temperature is increased [12][13][14][15]. The S 11 -T curve obtained in this work exhibits a sharper transition, demonstrating the improved sensitivity in our NSMM approach.…”

Near-Field Microwave Microscopy of Materials Properties

“…Already progress has been made in imaging the transition temperature in superconducting thin films [43,70,71,72]. Although a superconducting microscope is probably required to image surface impedance on the micron scale, it may be possible to learn more from conventional microscopes which study nonlinearities [52,54,73].…”