Room-Temperature Single-Molecule Conductance Switch via Confined Coordination-Induced Spin-State Manipulation
Jing Li, Qingqing Wu, Wei Xu, Haichuan Wang, Hewei Zhang, Yaorong Chen, Yongxiang Tang, Songjun Hou, Colin J. Lambert, Wenjing Hong
Abstract
The emerging of molecular spintronics offers a unique chance for the design of molecular devices with different spin-state, and the control of spin-state becomes essential for molecular spin switches. However, the intrinsic spin switching from low-spin to high-spin state is a temperature-dependent process with a small energy barrier that low temperature is required to maintain the low-spin state, and thus the room-temperature operation of single-molecule devices have not yet been achieved. Here, we present a reversible single-molecule conductance switch by manipulating the spin states of the molecule at room temperature using the scanning tunneling microscope break-junction (STM-BJ) technique. The manipulation of the spin states between S = 0 and S = 1 is achieved by complexing or decomplexing the pyridine derivative molecule with the square planar nickel(II) porphyrin. The bias-dependent conductance evolution proved that the strong electric field between the nanoelectrodes plays a crucial role in the coordination reaction. The DFT calculations further revealed that the conductance changes come from the geometry change of the porphyrin ring and spin-state switching of Ni(II) ion. Our work provides a new avenue to investigate room-temperature spin-related sensors and molecular spintronics.