Dataset for: "Mapping the flux penetration profile in a 2G-HTS tape at the microscopic scale: deviations from a classical critical state model"

Data collection method:

The primary datasets are scanning Hall microscopy (SHM) used to directly image the magnetic field component perpendicular to the surface of a 10 × 14 mm2 piece of 2G-HTS tape at different temperatures ranging from 88 K down to 65 K. The microscope used is a modified commercial low temperature scanning tunnelling microscope (STM) where the tunnelling tip has been replaced by a custom-fabricated GaAs chip. The Hall probe is patterned in the two-dimensional (2D) electron gas of a GaAs/AlGaAs heterostructure, defined by the intersection of two 0.8 μm wide wires situated ∼5 μm from the Au-coated corner of a deep mesa etch that acts as an integrated STM tip. The Hall probe is mounted at an angle of 1°−2° with respect to the sample plane, with the STM tip being the closest point to the sample surface [10]. The Hall probe with ∼0.8 μm spatial resolution and ∼5 mG Hz−1/2 minimum detectable field was approached at a point approximately 1 mm from one of the long edges of the tape and then retracted ∼1 μm for fast data collection. Two operation modes were used; a rapid ‘flying mode’ where the Hall sensor makes a rapid 2D scan of the maximum field of view, and a ‘local’ magnetometry mode whereby the sensor is parked above a desired location and the ‘local’ magnetic induction measured while sweeping an external magnetic field perpendicular to the plane of the sample. By systematically acquiring SHM images at regularly spaced points on a magnetic field cycle starting from the zero field-cooled state, a spatial map can be made of the critical state established around a hysteresis loop.

Data processing and preparation activities:

The SHM image data in the archive are raw as-captured data without any post-processing. The SHM data plotted are scaled by the values stated at the figure captions in the published paper.

Technical details and requirements:

SHM image datasets are formatted as the magnetic induction in Gauss measured at each point on a 64 × 64 array of pixel positions. At the measurement temperatures of 83 K, 77 K and 65 K this corresponds to a scan range of 18 µm×18 µm, 16 µm×16 µm and 14 µm×14 µm, respectively.