One of the most difficult problems in quantum materials is controlling the internal states of quantum systems. Even though they have the same number of electrons, single molecules can exhibit various quantum states at the most fundamental level. These states can have radically diverse features because they are linked to various electron configurations.
Controlling the electrical structure of individual molecules may enable significant advances in both fundamental science and technology. However, controlling the internal states of molecules remains a challenge, and realistic, scalable strategies for overcoming it have yet to be proposed.
Researchers from Aalto University and the University of Jyväskylä recently achieved an experimental breakthrough by demonstrating the ability to manipulate individual molecules’ quantum states using an electrically controlled substrate. Their investigation demonstrated how a particular two-dimensional substance called SnTe offers the instrumental means required to regulate molecular states.
The researchers’ approach is based on a substrate’s ability to tune the internal state of molecules as a result of internal electric fields. This mechanism, known as ferroelectric molecular switching, enables researchers to control individual molecules merely by applying a voltage to the substrate. The tactic is based on the significant external voltage tunability of SnTe, which results from a special quantum phenomenon known as ferroelectricity.
Professor Shawulienu Kezilebieke from the University of Jyväskylä said, “Our results demonstrate how we can control individual molecules using electrically-tunable two-dimensional materials. From a practical point of view, two-dimensional ferroelectrics have been instrumental, as its ultraclean interface allows realizing this strategy of quantum control. These experiments devised a strategy to engineer quantum states at the molecular level, opening exciting possibilities in artificial materials and single-molecule electronics.”
Ph.D. researcher Mohammad Amini, the first author of the study, said, “In our experiments, we demonstrated how two-dimensional ferroelectrics allow us to realize electrically switchable quantum states. Controlling quantum states electrically is a major milestone in quantum materials, and here we demonstrated one strategy for doing it at the deepest level of individual molecules.”
- Mohammad Amini, Orlando J. Silveira et al. Control of Molecular Orbital Ordering Using a van der Waals Monolayer Ferroelectric. Advanced Materials. DOI: 10.1002/adma.202206456