A Hall Microscope for Investigating High-Temperature Superconductors

Resumo

On the basis of Hall transducers, a three-dimensional scanning microscope with a sensitivity of ~2.5 × 10^–3 G/Hz^1/2 was designed. The dynamic range of the microscope with respect to the magnetic field ranges from 10^–3 to ±3 × 10³ G. The stability of a given magnetic field is better than 10^–5 G. The minimum value of steps when the magnetic field varies stepwise is 10^–3 G. The maximum survey area of the objects under study is 5 × 5 mm². The minimum scanning step sizes are 10 and 1 μm along the Х and Y axes, respectively, for rough and fine displacements of the tables. The maximum scanning size along the Z axis is 25 mm with minimum scanning steps of 10 and 1 μm, respectively, for rough and fine displacements. The microscope allows one to create an instrument function of an arbitrary shape due to a combination of the specified temperature, transport current, a dc magnetic field, and a time-oscillating ac magnetic field. Examples of applying the microscope to investigations of high-temperature BSCCO and YBCO superconductors are presented.