Chiral molecular intercalation superlattices

• Published in: Nature (London) 2022-06, Vol.606 (7916), p.902-908
• Main Authors: Qian, Qi, Ren, Huaying, Zhou, Jingyuan, Wan, Zhong, Zhou, Jingxuan, Yan, Xingxu, Cai, Jin, Wang, Peiqi, Li, Bailing, Sofer, Zdenek, Li, Bo, Duan, Xidong, Pan, Xiaoqing, Huang, Yu, Duan, Xiangfeng
• Format: Article
• Language: English
• Subjects: 140/133; 142/126; 639/301/1005/1007; 639/301/119/1001; 639/301/357/1018; Chemistry; Chiral materials; Chirality; Circular dichroism; Crystals; Dichroism; Electron microscopy; Handedness; Humanities and Social Sciences; Inhomogeneity; Intercalation; Magnetic fields; Magnetoresistance; Magnetoresistivity; multidisciplinary; Polarization (spin alignment); Robustness; Science; Science & Technology - Other Topics; Science (multidisciplinary); Selectivity; Self-assembly; Solid state; Superlattices; Transmission electron microscopy; X-ray diffraction
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-04846-3

The discovery of chiral-induced spin selectivity (CISS) opens up the possibility to manipulate spin orientation without external magnetic fields and enables new spintronic device designs 1 – 4 . Although many approaches have been explored for introducing CISS into solid-state materials and devices, the resulting systems so far are often plagued by high inhomogeneity, low spin selectivity or limited stability, and have difficulties in forming robust spintronic devices 5 – 8 . Here we report a new class of chiral molecular intercalation superlattices (CMIS) as a robust solid-state chiral material platform for exploring CISS. The CMIS were prepared by intercalating layered two-dimensional atomic crystals (2DACs) (such as TaS 2 and TiS 2 ) with selected chiral molecules (such as R-α-methylbenzylamine and S-α-methylbenzylamine). The X-ray diffraction and transmission electron microscopy studies demonstrate highly ordered superlattice structures with alternating crystalline atomic layers and self-assembled chiral molecular layers. Circular dichroism studies show clear chirality-dependent signals between right-handed (R-) and left-handed (S-) CMIS. Furthermore, by using the resulting CMIS as the spin-filtering layer, we create spin-selective tunnelling junctions with a distinct chirality-dependent tunnelling current, achieving a tunnelling magnetoresistance ratio of more than 300 per cent and a spin polarization ratio of more than 60 per cent. With a large family of 2DACs of widely tunable electronic properties and a vast selection of chiral molecules of designable structural motifs, the CMIS define a rich family of artificial chiral materials for investigating the CISS effect and capturing its potential for new spintronic devices. By intercalating layered 2D atomic crystals with selected chiral molecules, a new class of chiral molecular intercalation superlattices is reported, demonstrating highly ordered structures and achieving high tunnelling magnetoresistance and spin polarization ratios.