Patel Anand, Chowdhry Z, Prabhakar Anil, Rathi A, Bhallamudi Vidya Praveen
Quantum Center of Excellence for Diamond and Emergent Materials, Indian Institute of Technology Madras, Chennai, 600036, India.
Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
Sci Rep. 2024 Sep 28;14(1):22421. doi: 10.1038/s41598-024-73118-z.
Electronic spins associated with the Nitrogen-Vacancy (NV) center in diamond offer an opportunity to study spin-related phenomena with extremely high sensitivity owing to their high degree of optical polarization. Here, we study both single- and double-quantum transitions (SQT and DQT) in NV centers between spin-mixed states, which arise from magnetic fields that are non-collinear to the NV axis. We demonstrate the amplification of the ESR signal from both these types of transition under laser illumination. We obtain hyperfine-resolved X-band ESR signal as a function of both excitation laser power and misalignment of static magnetic field with the NV axis. This, combined with our analysis using a seven-level model that incorporates thermal polarization and double quantum relaxation, allows us to comprehensively analyze the polarization of NV spins under off-axis fields. Such detailed understanding of spin-mixed states in NV centers under photo-excitation can help greatly in realizing NV-diamond platform's potential in sensing correlated magnets and biological samples, as well as other emerging applications, such as masing and nuclear hyperpolarization.
由于具有高度的光学极化特性，与金刚石中的氮空位（NV）中心相关的电子自旋为研究自旋相关现象提供了一个以极高灵敏度进行研究的机会。在此，我们研究了NV中心在自旋混合态之间的单量子和双量子跃迁（SQT和DQT），这些跃迁源于与NV轴非共线的磁场。我们展示了在激光照射下这两种跃迁类型的电子自旋共振（ESR）信号的放大。我们获得了超精细分辨的X波段ESR信号，它是激发激光功率和静磁场与NV轴失准的函数。这一点，再结合我们使用包含热极化和双量子弛豫的七能级模型进行的分析，使我们能够全面分析离轴磁场下NV自旋的极化情况。对光激发下NV中心自旋混合态的这种详细理解，对于实现NV金刚石平台在传感相关磁体和生物样品以及其他新兴应用（如微波激射和核超极化）方面的潜力有很大帮助。
