Chiral molecular intercalation superlattices

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 TiS2) with selected chiral molecules (such as R-alpha-methylbenzylamine and S-alpha-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.

Automated summary

The discovery of chiral-induced spin selectivity (CISS) allows the manipulation of spin orientation without external magnetic fields, opening up new possibilities for spintronic device designs. However, current systems often suffer from issues such as high inhomogeneity, low spin selectivity, limited stability, and difficulties in forming robust spintronic devices. In this study, a new class of chiral molecular intercalation superlattices (CMIS) was developed as a solid-state chiral material platform for exploring CISS. The CMIS exhibited highly ordered superlattice structures and showed chirality-dependent signals, enabling the creation of spin-selective tunnelling junctions with significant tunnelling magnetoresistance ratio and spin polarization ratio. With the wide range of 2DACs and chiral molecules available, CMIS offer a rich family of artificial chiral materials to investigate the CISS effect and explore its potential for new spintronic devices.