Zhou Meng, Sarmiento Julio S, Fei Chengbin, Zhang Xinwen, Wang He
Department of Physics , University of Miami , Coral Gables , Florida 33146 , United States.
J Phys Chem Lett. 2020 Feb 20;11(4):1502-1507. doi: 10.1021/acs.jpclett.0c00004. Epub 2020 Feb 7.
Lead halide perovskites have been promising candidates in spintronics applications; however, the mechanism of spin relaxation is still unclear. Here, we compare the temperature-dependent spin dynamics of four perovskite films (XPbY) with different compositions (X = CHNH, Cs; Y = I, Br). The room-temperature net spin lifetime is found to increase as the molar mass decreases, indicating the dominant role of spin orbital coupling in their spin relaxation. As the temperature is reduced from room temperature to 77 K, the spin relaxations in CHNHPbI and CsPbI are significantly slowed down while those of CHNHPbBr and CsPbBr are only slightly changed. Based on the analysis of phonon scattering of perovskites, it is suggested that two different mechanisms, Elliot-Yafet in which spin flips upon momentum scattering and D'yakonov-Perel in which spin relaxes between momentum scattering, are responsible for the spin relaxation in XPbI and XPbBr (X = CHNH, Cs), respectively.
卤化铅钙钛矿一直是自旋电子学应用中有潜力的候选材料；然而，自旋弛豫的机制仍不清楚。在此，我们比较了四种不同组成（X = CHNH、Cs；Y = I、Br）的钙钛矿薄膜（XPbY）的温度依赖自旋动力学。发现室温下的净自旋寿命随摩尔质量降低而增加，表明自旋轨道耦合在其自旋弛豫中起主导作用。当温度从室温降至77 K时，CHNHPbI和CsPbI中的自旋弛豫显著减慢，而CHNHPbBr和CsPbBr中的自旋弛豫仅略有变化。基于对钙钛矿声子散射的分析，表明分别有两种不同机制导致XPbI和XPbBr（X = CHNH、Cs）中的自旋弛豫，一种是动量散射时自旋翻转的埃利奥特 - 亚费特机制，另一种是动量散射间自旋弛豫的迪亚科诺夫 - 佩雷尔机制。
