The micro-fabrication and performance analysis of non-magnetic heating chip for miniaturized SERF atomic magnetometer

The elevated temperature field is one of the fundamental conditions for the spin-exchange relaxation-free (SERF) regime, which can be accomplished by electric heating chip without introducing stray field. Therefore, a nonmagnetic heating chip composed of double identical ring-structure layers with a silicon oxide insulating layer between them is carefully designed and fabricated with the material of nichrome alloy on a borosilicate glass substrate by Micro Electro-Mechanical Systems (MEMS) technology. What's more, the influence of annealing treatment process on the microstructure of the heating chip is characterized and explicated utilizing modern surface science technique, including four-probe meter, X-ray diffraction (XRD) and atomic force microscope (AFM). Then, the integrated miniature single-beam SERF atomic magnetometer is developed based on the microfabricated heating chip. The temperature stability of heating chip is tested with the value less than +/- 10 mK at 120 degrees C by the proportional integral derivative (PID) control program, and the magnetic current coefficient is determined of only 0.506 nT/mA by the spin resonance response of the SERF atomic magnetometer near the zero field. Finally, the developed SERF atomic magnetometer achieves a high measuring sensitivity of 70 fT/Hz1/ 2. These experimental results provide a new avenue for the wafer-level microfabrication of the high-performance non-magnetic heating chip. More importantly, the presented work paves the way towards chip-scale atomic magnetometers with high sensitivity and mm-scale spatial resolution in the applications of magnetic source imaging and magnetic anomaly detection.

Automated summary

This study presents a spin-exchange relaxation-free (SERF) atomic magnetometer based on a non-magnetic heating chip. The heating chip is fabricated using microelectromechanical systems (MEMS) technology and its temperature stability and magnetic current coefficient are tested. The experimental results show high measuring sensitivity, indicating the potential application of this atomic magnetometer in magnetic source imaging and magnetic anomaly detection.