High-Tc superconducting gradiometer with a long baseline asymmetric flux transformer

The planar gradiometer consists of a directly coupled magnetometer inductively coupled to the smaller loop of an asymmetric, two-loop flux transformer patterned in a single film of YBa2Cu3O7−x. The coupling is adjusted mechanically to balance the gradiometer to about 1 part in 3000 with respect to fields perpendicular to its plane. The baseline is 48 mm and the intrinsic balance with respect to in-plane fields about 1 part in 1400. When a magnetic field is applied solely to the magnetometer, its sensitivity is reduced by only 5% by the presence of the flux transformer.