Miniature Hall sensor based ac susceptometer for measurements of vortex and superfluid dynamics in superconducting films

Abstract

A highly sensitive ac susceptometer has been fabricated using a commercially available thin film Hall sensor of effective area 25×25 μm2. This instrument allows measurements of superfluid density and dynamical behavior of vortices in thin film superconductors over a broad range of frequency (10 Hz–100 kHz), temperature (4.2–300 K), and ac-field amplitude (2–150 Oe), and in static magnetic field as high as 5 T collinear with the ac field. The applicability of the susceptometer has been tested on Y1Ba2Cu3O7 films of thickness as small as ∼7 nm.