Conductance Peak Splitting in the Coulomb Blockade as Signature of Spin Interactions

Multi-spin device setups, such as triple quantum dots and dimer arrangements of magnetic molecules, show favorable characteristics for their use as spintronic and scalable quantum information devices^[1,2]. There is a need to characterize single-electron transport properties of these systems to guide experimental realizations. In a step towards this aim, we use the generalized master equation under the Born and Markov approximation for a dimer system coupled to spin-polarized leads, with energy level positions controlled by a gate voltage, under an applied magnetic field. We predict multiple peaks in the steady-state conductance, as opposed to the single peak expected in traditional Coulomb blockade single molecule magnet experiments, related to the inclusion of excited state transitions between uncharged and charged electron manifolds. We find that by adjusting the exchange coupling of the electron with the system, these features turn on and off. This prediction opens the possibility of using spin-polarized current measurements to measure the exchange coupling between the iterant electron and multi-spin system.

[1] J. Z. Blumof, et al., PRX Quantum 3, 010352 (2022)

[2] E. D. Switzer, X.-G. Zhang, T. S. Rahman, PRA 104, 052434 (2021)