Detection of Spin Interactions with Single Magnetic Molecules*

Magnetic single molecules are receiving intensifying research focus because they are promising candidates for realizing the spatial limit of memory storage and qbits. Scanning tunneling microscopy (STM) offers particular experimental advantages given its ability to image and characterize single atoms and molecules. With an ultrahigh vacuum sub-Kelvin high magnetic field STM, inelastic electron tunneling spectroscopy (IETS) can be used to study the spin-flip dynamics of single atoms and molecules as well as to characterize Zeeman splitting with respect to the external magnetic field. Here, we successfully prepared Al₂O₃ film by partial oxidation the atomic clean NiAl(110) surface and deposited NiCp₂  (short for Ni(cyclopentadienyl)₂) molecules on both NiAl(110) surface as well as the Al₂O₃ films. The magnetic anisotropy of energy (MAE) of NiCp₂ molecules adsorbed on different sites are measured. We showed that the MAE of NiCp₂ molecules varies with adsorption geometry. The spin-vibration coupled transitions of NiCp₂ molecules and the spin exchange interaction between two NiCp₂ molecules are also observed. With NiCp₂ Adsorbed at the apex of the STM tip, exchange interactions with another molecule adsorbed on NiAl(110) surface are dectected.