在CsPbI$_3$铅卤化物纳米晶中揭示毫秒级电子自旋寿命
Millisecond-long electron spin lifetime in CsPbI$_3$ perovskite nanocrystals revealed by optically detected magnetic resonance
AI总结：
通过光学检测磁共振技术，发现CsPbI$_3$纳米晶中电子自旋寿命可达毫秒级，揭示了核场波动对自旋弛豫的影响。
摘要：
铅卤化物纳米晶是一种方便的光学自旋取向和操控的模型系统。然而，由于对自旋弛豫时间的不完全了解，其真实潜力可能被低估，这主要是由于测量技术的灵敏度有限以及对铅卤化物中自旋弛豫机制理解不足所致。在本工作中，我们通过实验和理论研究了铅卤化物纳米晶中的自旋弛豫。我们通过基于光学检测磁共振的共振自旋惯性技术，研究了嵌入玻璃基质中的CsPbI$_3$纳米晶中的电子和空穴自旋。该技术使我们能够分别确定电子和空穴的纵向自旋弛豫时间$T_1$、$g$因子以及核自旋浴的有效Overhauser场。在1.6 K的温度下，电子的$T_1$时间可达到0.9毫秒。我们揭示了时间变化的核场波动的影响，该影响在低磁场下增强了电子自旋弛豫，并测量了相对较长的核自旋相关时间，约为60微秒。我们基于双LO声子拉曼过程发展了一个纳米晶中自旋弛豫的模型，该模型解释了观测到的$T_1$时间的温度依赖性。
英文摘要：
Perovskite nanocrystals are a convenient model system for optical spin orientation and manipulation. However, its real potential might be underestimated due to the incomplete knowledge on spin relaxation times, which are obscured by the limited sensitivity of measurement techniques as well as by the insufficient understanding of the spin relaxation mechanisms in perovskites. In this work, we study the spin relaxation of charge carriers in perovskite nanocrystals both experimentally and theoretically. We address the electron and hole spins in CsPbI$_3$ nanocrystals embedded in a glass matrix by the resonant spin inertia technique based on optically detected magnetic resonance. It allows us to determine the longitudinal spin relaxation time $T_1$ separately for electrons and holes, the $g$ factors, and the effective Overhauser field of the nuclear spin bath. At a temperature of 1.6 K, the $T_1$ time for electrons can be as long as 0.9 ms. We reveal the effect of the time-varying nuclear field fluctuations, which enhances the electron spin relaxation at low magnetic fields, and measure a rather long nuclear spin correlation time of about 60 $μ$s. We develop a model of the spin relaxation in nanocrystals based on a two-LO-phonon Raman process, which explains the observed temperature dependence of the time $T_1$.
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