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arXiv 1807.08889cond-mat.mtrl-scicond-mat.mes-hall
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NV - -1b菱形中的N+对中心

NV- - N+ pair centre in 1b diamond

Neil B. Manson, Morgan Hedges, Michael S, J. Barson, Rose Ahlefeldt, Marcus W. Doherty, Matthew J. Sellars, Hiroshi Abe, Takeshi Ohshima

摘要:

该研究确定,在1b金刚石中NV $^- $可实现的光致自旋极化的程度受限于单取代氮N $^0$的浓度。金刚石中各个NV中心的极化取决于NV $^-$和氮供体的分离。当NV $^-$ - N $^+$对间距大时,该对的性质将与单位点相同,并且可获得高度的自旋极化。当间距减小时,发射减少,寿命缩短,自旋极化降低。劣化是由于从NV $^-$到N $^+$的激发态中的电子隧穿而发生的,并且导致包括NV $^0$的光学循环。隧穿过程在光激发中是线性的,并且N $^+$越接近NV $^-$中心越普遍。然而,NV $^-$和其供体N $^+$之间的分离可以通过NV $^-$的激发和/或N $^0$的电离由光实现。产生自旋极化的光学激发也可以改变样品的性质,并且在激发期间产生电荷动力学。结果是自旋极化的大小、自旋弛豫和相干时间T $_1$和T $_2$依赖于氮浓度和激发波长。相邻的N $^+$提供了一个电场,使NV $^-$跃迁发生斯塔克位移,并且对于系综,导致谱线加宽。通过观察这些斯塔克诱导效应的变化,可以监测NV $^-$ - N $^+$分离的变化。光谱测量包括不同线宽的测量是这项研究的核心。它们是在低温下进行的,包括在637 nm处的NV $^-$光学跃迁、在1042 nm处的红外跃迁和在2.87 GHz处的ODMR的广泛测量。

英文摘要:

The study establishes that the degree of optically induced spin polarization that can be achieved for NV$^- $in 1b diamond is limited by the concentration of single substitutional nitrogen, N$^0$ . The polarization of the individual NV centres in the diamond is dependent on the separation of the NV$^-$ and the nitrogen donor. When the NV$^-$ - N$^+$ pair separation is large the properties of the pair will be as for single sites and a high degree of spin polarization attainable. When the separation decreases the emission is reduced, the lifetime shortened and the spin polarization downgraded. The deterioration occurs as a consequence of electron tunneling in the excited state from NV$^-$ to N$^+$ and results in an optical cycle that includes NV$^0$. The tunneling process is linear in optical excitation and more prevalent the closer the N$^+$ is to the NV$^-$ centre. However, the separation between the NV$^-$ and its donor N$^+$ can be effected by light through the excitation of NV$^-$ and/or ionization of N$^0$. The optical excitation that creates the spin polarization can also modify the sample properties and during excitation creates charge dynamics. The consequence is that the magnitude of spin polarization, the spin relaxation and coherence times T$_1$ and T$_2$ have a dependence on the nitrogen concentration and on the excitation wavelength. The adjacent N$^+$ gives an electric field that Stark shifts the NV$^-$ transitions and for an ensemble results in line broadening. It is observation of changes of these Stark induced effects that allow the variation in NV$^-$ - N$^+$ separation to be monitored. Spectroscopic measurements including that of the varying line widths are central to the study. They are made at low temperatures and include extensive measurements of the NV$^-$ optical transition at 637 nm, the infrared transition at 1042 nm and ODMR at 2.87 GHz.

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