It is demonstrated that the sensitivity of a standard Hall magnetometer can be increased from similar to 2.5 x 10(-3) to similar to 8 x 10(-7) G/Hz(1/2). The increase in the sensitivity is achieved due to the use of a sharp jump of the magnetic response of an HTSC (YBa2Cu3O7-x) epitaxial film located on the surface of a Hall transducer at the first thermodynamic critical magnetic field H-ic1 of twins. To increase the sensitivity, linearity, and noise immunity of the magnetometer, the working point is shifted to the value of H-ic1 of twins by applying a constant support magnetic field as well as a decaying oscillating local bias field. This total field directed perpendicular to the film surface also provides an increase in the spatial resolution of the magnetometer, which is determined by the linear size of twins in the YBCO film. This size reaches similar to 300 nm (with a decrease to 20 nm for the appropriate minimal size of the twins). The design of the magnetometer allows measurements of not only dc but also ac magnetic fields in the range from 10(-7) to 10(-3) Oe at a frequency of 1 kHz, while preserving the high performance of the magnetometer. With the use of high-frequency magnetic-field transducers, the magnetometer can operate in the frequency range of up to 100 kHz and detect both alternating and pulsed magnetic fields.
展开▼
