Wide-range and self-locking atomic magnetometer based on free spin precession

The magnetic field is one of the most fundamental and ubiquitous physical observables, often conveying rich information about its generation source. Atomic magnetometers have been proven to be high-potential techniques for weak magnetic field measurement in various applications. However, due to the lack of excellent frequency-locking ability against abrupt magnetic field changes, atomic magnetometers are limited to use in application scenarios, which require both wide-range and self-locking characteristics. In this paper, theoretical and experimental research for a wide-range and self-locking rubidium atomic magnetometer based on free spin precession is presented. The rubidium atomic magnetometer can track a magnetic field jump of 10,000 nT in the measurement range from 500 nT to 100,500 nT. We also investigate the bandwidth and dead zone of the atomic magnetometer. An atomic magnetometer with excellent self-locking ability in a wide range can be developed into new highly sensitive magnetic measuring devices, enabling geomagnetic measurement in real environments and monitoring the magnetic phase transitions or coercive fields of soft magnetic materials in very magnetic-shielding environments.