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

• Published in: Journal of magnetism and magnetic materials 2022-09, Vol.557, p.169495, Article 169495
• Main Authors: Ma, Yintao, Chen, Yao, Zhao, Libo, Luo, Guoxi, Yu, Mingzhi, Wang, Yanbin, Guo, Ju, Yang, Ping, Lin, Qijing, Jiang, Zhuangde
• Format: Article
• Language: English
• Subjects: Annealing treatment; Chip-scale atomic magnetometer; Magnetic current coefficient; Non-magnetic heating chip; SERF regime
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2022.169495

•A Micro Electro-Mechanical Systems (MEMS) non-magnetic heating chip is carefully designed and fabricated with the material of nichrome alloy on the borosilicate glass substrate.•The influence of annealing treatment process on the microstructure of the heating chip is characterized utilizing modern surface science technique, including four-probe meter, X-ray diffraction (XRD) and atomic force microscope (AFM).•An integrated miniature single-beam Cs-Ne SERF atomic magnetometer is developed based on the microfabricated non-magnetic heating chip with the magnetic field sensitivity of 70 fT/Hz1/2.•The presented work paves the way towards chip-scale atomic magnetometers with high measuring sensitivity and mm-scale spatial resolution in the applications of magnetic source imaging and quantum navigation. 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 non-magnetic 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 °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.