Hall-array gradiometer for measurement of the magnetic induction vector in superconductors

An experimental technique for measuring the distribution of the normal and planar components of the magnetic induction near the surface of a superconducting sample is described. This technique utilizes a design of a double-layered Hall sensor array fabricated from a GaAs/AlGaAs heterostructure containing two parallel layers of a two-dimensional electron gas. Applications of this technique are demonstrated in measuring the current density distribution and in characterizing the flux creep process in a thin YBa2Cu3O7 crystal. (C) 1999 American Institute of Physics. [S0021-8979(99)31408-0].