Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM, USA.
Laser Centre, University of Latvia, Riga, Latvia.
Sci Adv. 2023 Jun 16;9(24):eadh3189. doi: 10.1126/sciadv.adh3189.
Radio frequency (RF) magnetometers based on nitrogen vacancy centers in diamond are predicted to offer femtotesla sensitivity, but previous experiments were limited to the picotesla level. We demonstrate a femtotesla RF magnetometer using a diamond membrane inserted between ferrite flux concentrators. The device provides ~300-fold amplitude enhancement for RF magnetic fields from 70 kHz to 3.6 MHz, and the sensitivity reaches ~70 fT√s at 0.35 MHz. The sensor detected the 3.6-MHz nuclear quadrupole resonance (NQR) of room-temperature sodium nitrite powder. The sensor's recovery time after an RF pulse is ~35 μs, limited by the excitation coil's ring-down time. The sodium-nitrite NQR frequency shifts with temperature as -1.00±0.02 kHz/K, the magnetization dephasing time is *=887±51 μs, and multipulse sequences extend the signal lifetime to 332±23 ms, all consistent with coil-based studies. Our results expand the sensitivity frontier of diamond magnetometers to the femtotesla range, with potential applications in security, medical imaging, and materials science.
基于金刚石中氮空位中心的射频（RF）磁强计预计将提供飞特斯拉灵敏度，但以前的实验仅限于皮特斯拉水平。我们使用插入铁氧体磁通集中器之间的金刚石膜演示了一种飞特斯拉 RF 磁强计。该器件为 70 kHz 至 3.6 MHz 的射频磁场提供了约 300 倍的幅度增强，在 0.35 MHz 时灵敏度达到约 70 fT√s。该传感器检测到室温亚硝酸钠粉末的 3.6-MHz 核四极共振（NQR）。RF 脉冲后的传感器恢复时间约为 35 μs，这受到激励线圈的衰减时间的限制。亚硝酸钠 NQR 频率随温度变化为-1.00±0.02 kHz/K，磁化退相时间为 *=887±51 μs，多脉冲序列将信号寿命延长至 332±23 ms，这些都与基于线圈的研究一致。我们的结果将金刚石磁强计的灵敏度扩展到飞特斯拉范围，在安全、医学成像和材料科学等领域具有潜在应用。
