Circular photogalvanic spectroscopy of Rashba splitting in 2D hybrid organic-inorganic perovskite multiple quantum wells
Circular photogalvanic spectroscopy of Rashba splitting in 2D hybrid organic-inorganic perovskite multiple quantum wells
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DOI：
10.1038/s41467-019-14073-6
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发表时间：
2020-01-16
影响因子：
16.6
通讯作者：
Vardeny, Z. V.
中科院分区：
文献类型：
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作者：
Liu, Xiaojie;Chanana, Ashish;Vardeny, Z. V.
二维（2D）Ruddlesden-Popper有机-无机卤化物钙钛矿如（2D）-苯乙基铵碘化铅（2D-PEPI）具有类似于多量子威尔斯（MQW）的层状结构。2D-PEPI中的重原子贡献了较大的自旋轨道耦合，影响了电子能带结构。在破坏反转对称性时，在电子带中发生自旋分裂（“Rashba分裂”）。利用圆形光电流效应研究了2D-PEPI单晶的自旋劈裂。我们证实了在3510 meV电子带极值处存在Rashba分裂，并确定了垂直于多量子阱平面的主要反转对称性破缺方向。带隙上方的CPGE作用光谱揭示了由在动量空间中分离的激发光载流子的超快弛豫产生的自旋极化光电流。而带隙下激发的螺旋度依赖的光电流是由于电离的自旋极化激子的自旋电流效应，其中自旋极化发生在自旋分裂带中，由于不对称的自旋翻转。
The two-dimensional (2D) Ruddlesden-Popper organic-inorganic halide perovskites such as (2D)-phenethylammonium lead iodide (2D-PEPI) have layered structure that resembles multiple quantum wells (MQW). The heavy atoms in 2D-PEPI contribute a large spin-orbit coupling that influences the electronic band structure. Upon breaking the inversion symmetry, a spin splitting ('Rashba splitting') occurs in the electronic bands. We have studied the spin splitting in 2D-PEPI single crystals using the circular photogalvanic effect (CPGE). We confirm the existence of Rashba splitting at the electronic band extrema of 3510meV, and identify the main inversion symmetry breaking direction perpendicular to the MQW planes. The CPGE action spectrum above the bandgap reveals spin-polarized photocurrent generated by ultrafast relaxation of excited photocarriers separated in momentum space. Whereas the helicity dependent photocurrent with below-gap excitation is due to spin-galvanic effect of the ionized spin-polarized excitons, where spin polarization occurs in the spin-split bands due to asymmetric spin-flip.