Gao Xingyu, Vaidya Sumukh, Dikshit Saakshi, Ju Peng, Shen Kunhong, Jin Yuanbin, Zhang Shixiong, Li Tongcang
Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA.
Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA.
Nat Commun. 2024 Sep 4;15(1):7697. doi: 10.1038/s41467-024-51941-2.
Optically addressable spin defects in three-dimensional (3D) crystals and two-dimensional (2D) van der Waals (vdW) materials are revolutionizing nanoscale quantum sensing. Spin defects in one-dimensional (1D) vdW nanotubes will provide unique opportunities due to their small sizes in two dimensions and absence of dangling bonds on side walls. However, optically detected magnetic resonance of localized spin defects in a nanotube has not been observed. Here, we report the observation of single spin color centers in boron nitride nanotubes (BNNTs) at room temperature. Our findings suggest that these BNNT spin defects possess a spin S = 1/2 ground state without an intrinsic quantization axis, leading to orientation-independent magnetic field sensing. We harness this unique feature to observe anisotropic magnetization of a 2D magnet in magnetic fields along orthogonal directions, a challenge for conventional spin S = 1 defects such as diamond nitrogen-vacancy centers. Additionally, we develop a method to deterministically transfer a BNNT onto a cantilever and use it to demonstrate scanning probe magnetometry. Further refinement of our approach will enable atomic scale quantum sensing of magnetic fields in any direction.
三维（3D）晶体和二维（2D）范德华（vdW）材料中的光学可寻址自旋缺陷正在革新纳米级量子传感。一维（1D）vdW纳米管中的自旋缺陷由于其二维尺寸小且侧壁无悬键，将提供独特的机会。然而，尚未观察到纳米管中局域自旋缺陷的光学检测磁共振。在此，我们报告了在室温下氮化硼纳米管（BNNTs）中单个自旋色心的观测结果。我们的研究结果表明，这些BNNT自旋缺陷具有自旋S = 1/2基态，没有固有量子化轴，从而实现与取向无关的磁场传感。我们利用这一独特特性，观察二维磁体在正交方向磁场中的各向异性磁化，这对于诸如金刚石氮空位中心等传统自旋S = 1缺陷来说是一项挑战。此外，我们开发了一种方法，可将BNNT确定性地转移到悬臂上，并用于演示扫描探针磁力测量。对我们方法的进一步改进将实现对任何方向磁场的原子尺度量子传感。
