using Graphene Quantum Dots*

Transport measurements through a graphene quantum dot device decorated with single-molecule magnet (SMM) Mn₁₂ powder indicate stochastic switching of the magnetization in the molecules. Here we show that discrete changes in the graphene conductance can be attributed to magnetic switching of the molecules. The local magnetic field causes a change in the activation energy of the hot electrons in the quantum dot [1], allowing the graphene device to serve as a sensitive detector for the spin state of the proximate molecules and as a probe to measure the interaction between the SMMs and the graphene. The size of the activation energy change is too large to be explained by Zeeman effects owing to the dipole field, suggesting an exchange bias interaction between the graphene and the molecules.

 

[1] A. El Fatimy et al. Nature Nanotechnology 11, 335-338 (2016)