Li Chuanzhao, Telychko Mykola, Zheng Yue, Yuan Shurong, Wu Zhenyue, Wong Walter P D, Li Yixin, Jin Yuanyuan, Io Weng Fu, Wang Xinyun, Lin Junhao, Hao Jianhua, Han Cheng, Leng Kai
Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA.
Nat Commun. 2024 Nov 25;15(1):10221. doi: 10.1038/s41467-024-54524-3.
Chiral organic-inorganic hybrid perovskites offer a promising platform for developing non-linear chiro-optical applications and chiral-induced spin selectivity. Here, we show that achiral hybrid perovskites that have highly ordered ferroelectric domains with orthogonal polarization exhibit planar chirality, as manifested by second harmonic generation with strong circular dichroism. Interestingly, the handedness of the second harmonic generation circular dichroism response can be alternatingly switched between orthogonally polarized domains and domain walls. To correlate the origin of planar chirality in these domains, atom-resolved atomic force microscopy is used to reveal distinct arrangements of atomic rows in these ferroelectric crystals that indicate planar symmetry breaking. Remarkably, a large SHG anisotropy factor of 0.41 is measured at the domain wall. Additionally, spatially resolved two-photon photoluminescence excitation measurement provide evidence of larger Rashba spin-splitting in these chiral ferroelectric domains compared to domain-free areas. Our discoveries of domain-dependent planar chirality and spin texture hold great promise for advancement of domain-specific chiro-optical applications.
手性有机-无机杂化钙钛矿为开发非线性手性光学应用和手性诱导自旋选择性提供了一个有前景的平台。在此，我们表明，具有高度有序铁电畴且极化相互正交的非手性杂化钙钛矿表现出平面手性，这通过具有强圆二色性的二次谐波产生得以体现。有趣的是，二次谐波产生圆二色性响应的旋向性可以在正交极化畴和畴壁之间交替切换。为了关联这些畴中平面手性的起源，利用原子分辨原子力显微镜揭示了这些铁电晶体中原子行的不同排列，这表明平面对称性被打破。值得注意的是，在畴壁处测得的二次谐波产生各向异性因子高达0.41。此外，空间分辨双光子光致发光激发测量提供了证据，表明与无畴区域相比，这些手性铁电畴中存在更大的Rashba自旋分裂。我们对依赖于畴的平面手性和自旋纹理的发现为特定畴手性光学应用的发展带来了巨大希望。
