image: Using a Kelvin probe force microscope, scientists visualized how chiral perovskites regulate electron spin, offering new insights that could guide the design of next-generation spintronic devices.
Credit: ©Science China Press
Chiral halide perovskites are attracting attention for their ability to control electron spin, a property known as the chiral-induced spin selectivity (CISS) effect. This effect allows these materials to control charge, spin, and light at room temperature, making them promising candidates for opto-spintronic applications. By harnessing the spin-degrees of freedom of charge carriers in semiconductor structures, these materials hold great potential for improving the efficiency of data storage and transfer. This is especially valuable in quantum computing and neuromorphic computing, where controlling spin-polarized currents could transform information processing.
Despite their potential, the CISS effect in chiral perovskites has been difficult to study at the microscopic scale. Conventional techniques detect the effect but may not provide detailed maps of its spatial variation within materials.
To address this challenge, researchers from the Ningbo Institute of Materials Technology and Engineering (Chinese Academy of Sciences), the Hong Kong University of Science and Technology, and the U.S. National Renewable Energy Laboratory developed a custom Kelvin probe force microscopy (KPFM) system. This approach enabled them to scan the same region of chiral perovskite thin films under different magnetic conditions, generating nanoscale “spin maps” that reveal both the strength and spatial uniformity of the CISS effect.
The study also discovered the presence of spin–Schottky junctions at the interface between chiral perovskites and metal electrodes. In these junctions, the energy barrier for electron flow shifts depending on spin orientation, offering new insights into how spin-dependent processes operate at material interfaces.
Further analysis revealed that factors such as chiral cations, film thickness, and processing conditions influence the strength of the spin-selective effect. The researchers also observed nanoscale variations across films, suggesting that spatial inhomogeneity could limit device performance.
This work establishes a non-destructive, quantitative method for probing spin-selective effects in chiral perovskites and provides a new framework for understanding how these materials function at the nanoscale. The results highlight key considerations for optimizing chiral perovskites in future spintronic and optoelectronic applications.
Journal
National Science Review