Berry-phase effect in single molecule magnets: analytical and numerical results

TL;DR

This paper investigates how Berry-phase interference affects electron transport in single molecule magnets, showing current blockade due to magnetic field manipulation using analytical and numerical methods.

Contribution

It introduces an effective Hamiltonian capturing Berry phase effects and demonstrates current blockade in a single molecule magnet transistor with polarized leads.

Findings

Berry phase causes current blockade in the device.

Effective Hamiltonian accurately models interference effects.

Numerical simulations match analytical predictions.

Abstract

In this paper we theoretically and numerically investigate transport signatures of quantum interference on the current through a single molecule magnet transistor tunnel coupled to oppositely polarized leads in the presence of a local transverse and longitudinal magnetic field. Our calculations are based in a density matrix approach where we treat the ground state energy splitting induced by tunneling of the spin between different paths with the aid of perturbation theory. Using this approach we show that it is possible to use an effective Hamiltonian which describes the Berry phase interference as a function of the transverse magnetic field which completely blocks the current flow when we place the single molecule magnet between oppositely polarized leads. Finally, we use this effective Hamiltonian in an open source Python software (QmeQ) that allows us to calculate the current through the single molecule magnet with oppositely polarized leads tunnel coupled to the single molecule magnet. The analytical results are well reproduced by our numerical simulations.