使用飞特斯拉级金刚石磁力仪进行核四极共振谱学
Nuclear quadrupole resonance spectroscopy with a femtotesla diamond magnetometer
AI总结：
本文提出一种基于NV掺杂金刚石薄膜与铁氧体磁通集中器的飞特斯拉级射频磁力仪，在0.35 MHz处灵敏度约70 fT s^{1/2}，并成功检测室温下亚硝酸钠粉末中14N的3.6 MHz核四极共振信号，将金刚石磁力仪灵敏度推进至飞特斯拉级。
摘要：
能够检测飞特斯拉级振荡磁场的灵敏射频（RF）磁力仪是核四极共振（NQR）谱学等高要求应用所必需的。基于金刚石中氮-空位（NV）色心的射频磁力仪已被预测可提供飞特斯拉级灵敏度，但已发表的实验大多局限于皮特斯拉级。在此，我们展示了一种基于插入两个铁氧体磁通集中器之间的NV掺杂金刚石薄膜的飞特斯拉级射频磁力仪。该器件在2-10微特斯拉的偏置磁场下工作，对于0.07-3.6 MHz范围内的射频磁场，在金刚石内部提供约300倍的幅度增强。该磁力仪在0.35 MHz处的灵敏度约为70 fT s^{1/2}，采集1小时后噪声底降至2 fT以下。我们使用该传感器在室温下检测了亚硝酸钠粉末中14N的3.6 MHz NQR信号。NQR信号由缠绕在样品周围的谐振射频线圈放大，从而实现更高信噪比的检测。金刚石射频磁力仪在强射频脉冲后的恢复时间约为35微秒，受限于线圈的振铃衰减时间。亚硝酸钠的NQR频率随温度线性变化，斜率为-1.00 ± 0.02 kHz/K，磁化退相干时间为T2* = 887 ± 51微秒，自旋锁定自旋回波脉冲序列将信号寿命延长至332 ± 23毫秒，这些结果均与基于线圈的NQR研究一致。我们的结果将金刚石磁力仪的灵敏度前沿拓展到飞特斯拉范围，在安全检测、医学成像和材料科学中具有潜在应用。
英文摘要：
Sensitive Radio-Frequency (RF) magnetometers that can detect oscillating magnetic fields at the femtotesla level are needed for demanding applications such as Nuclear Quadrupole Resonance (NQR) spectroscopy. RF magnetometers based on Nitrogen-Vacancy (NV) centers in diamond have been predicted to offer femtotesla sensitivity, but published experiments have largely been limited to the picotesla level. Here, we demonstrate a femtotesla RF magnetometer based on an NV-doped diamond membrane inserted between two ferrite flux concentrators. The device operates in bias magnetic fields of 2-10 microtesla and provides a ~300-fold amplitude enhancement within the diamond for RF magnetic fields in the 0.07-3.6 MHz range. The magnetometer's sensitivity is ~70 fT s^{1/2} at 0.35 MHz, and the noise floor decreases to below 2 fT after 1 hour of acquisition. We used this sensor to detect the 3.6 MHz NQR signal of 14N in sodium nitrite powder at room temperature. NQR signals are amplified by a resonant RF coil wrapped around the sample, allowing for higher signal-to-noise ratio detection. The diamond RF magnetometer's recovery time after a strong RF pulse is ~35 us, limited by the coil ring-down time. The sodium-nitrite NQR frequency shifts linearly with temperature as -1.00 +/- 0.02 kHz/K, the magnetization dephasing time is T2* = 887 +/- 51 us, and a spin-lock spin-echo pulse sequence extends the signal lifetime to 332 +/- 23 ms, all consistent with coil-based NQR studies. Our results expand the sensitivity frontier of diamond magnetometers to the femtotesla range, with potential applications in security, medical imaging, and materials science.
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