One dimensional spin-quantum transport in molecular wires – MQwires

Current industrially exploited technologies for the fabrication of nanoscale devices and further improvements of new kind of consumer electronics are based on the down-scaling of conventional semi-conductor technology. The inclusion of organic materials is so far limited to the optimization of material properties such as improved photon yield and color quality in OLEDs or mechanical flexibility for new kind of bendable user-adapted devices. The potential of organic and inorganic molecular systems in terms of self-ordering and more important, of self-formation of covalently bonded systems on the atomic scale which are self-evidently present in living organism but technologically so far non-reproducible, remains unused. Classical, i.e. solution based chemistry is a powerful approach for the synthesis of multi-functional nano-objects beyond the resolution limits of conventional fabrication techniques. However, once synthesized such multi-functional molecules become fragile and respectively, the incorporation into devices is strictly limited by available transfer methods. Furthermore, the synthesis routes are restricted by definition to soluble targets.
This project aims at carrying out the synthetic steps directly onto surfaces. The project gathers three experts, one (Fr) established in the synthesis of molecular units for molecular electronics and two (Tw) on the investigation of properties for molecular electronics and spintronics by physical methods (PES and STM). New routines on on-surface hetero-coupling sequences are investigated and their application in single molecule spin-junctions realized. At the CEMES-CNRS, new reactive groups will be synthesized and applied to spin-carrying molecular moieties. In parallel, respectively functionalized electronic and magnetic molecular units will be designed for the direct investigation of local physical properties in molecular spin-wires and -triangles. The groups at the National Tsing-Hua University will explore the physical properties and observe the chemical reactivity and induced reactions of substituents with Ultra-High Vacuum Scanning Tunneling Microscopy, Spectroscopy and Photoemission spectroscopy. During the course of this project, both approaches, i.e. synthesis of central functional physical units and of reactive substituents for hetero-coupling sequences will be merged towards the devices design.
To summarize, the ultimate goal of this project is to prepare directly on the surface, in a fully controlled manner, single-molecule devices comprising molecular wires/triangles and spin active elements of predefined length and sequence. The intrinsic spin-spin interaction and spin transport properties as well as the effect of external perturbations through a spin-polarized electron source and an external magnetic field of these devices will be explored.
The expected deliverables are the mastering of on-surface hetero-coupling, an improved understanding of the fundamental physical processes of the spin communication in the so-formed molecular quantum spin wires, and the fabrication of single-molecule spin-devices with predefined electronic/magnetic properties.