High-speed two-stage Hall magnetometer with increased resolution

Abstract

It is demonstrated that the use of two coaxial solenoids instead of one in the magnetic field sensor cell allows one to divide the dynamic range of the magnetometer into a wide range of support magnetic field and a narrow range of bias field. This makes it possible to design, on the basis of a Hall sensor, a two-stage magnetometer with resolution of about 8·10 –11 Т. An increase in the speed of the magnetometer is achieved due to the use of a weak bias field, which represents a decaying oscillating local magnetic field (DOLMF). The leading edge of the DOLMF is used to search for a signal to be measured by a servo-system, while its decaying part after switching off the magnetic field step does not lead to magnetic relaxation in the sensitive element made of a superconducting YBa 2 Cu 3 O 7– x epitaxial film due to the fast process of vortex–antivortex annihilation. The design of the proposed magnetometer provides a high-speed measurement of not only constant but also alternating magnetic fields in the range from 10 –11 to 10 –7 Т at a frequency of up to ∼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 measure both alternating and pulsed magnetic fields. • The use of two coaxial solenoids allows the design of a two-stage magnetometer with high resolution. • A superconducting epitaxial YBCO film is used as the sensitive element of the magnetometer. • The magnetometer provides a high-speed measurement of both constant and alternating magnetic fields.