Berry phase interference and single-electron transport in a three-ion magnetic molecule
We study single-electron transport in a magnetic molecule by using a stationary rate equation approach. In the molecule, two magnetic ions and are connected to each other through a third, nonmagnetic ion. The magnetic ions are coupled to ideal metallic leads and a back gate voltage is applied to the molecule, forming a field-effect transistor. A Hamiltonian which includes inter-ion hopping, on-site repulsion, and magnetic anisotropies is employed to describe this molecule, resulting in an energy spectrum similar to that of single molecule magnets in the giant-spin approximation. An external in-plane magnetic field is then used to drive the molecule to a diabolical point, where states with maximum total spin with opposite directions are degenerated. Both linear and nonlinear transport are evaluated near the diabolical point, showing features that can be attributed to Berry-phase interference of spin tunneling paths.