A Monte Carlo Evaluation of the Current and Low Frequency Current Noise at Spin-Dependent Hopping
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Monte Carlo methods are convenient to model the electron transport due to single electron hopping. The algorithm allows to incorporate a restriction that due to the Coulomb repulsion each trap can only be occupied by a single electron. With electron spin gaining increasing attention, the trap-assisted electron transport has to be generalized to include the electron spin, especially in the presence of an external magnetic field and with transport between ferromagnetic contacts. An innovative Monte Carlo method to deal with the spin-dependent hopping is presented. When the electron spin is taken into account, the escape transition rates are described by transition matrices which describe the coupled spin and occupation relaxation from the trap. The transport process is represented by a cyclic repetition of consecutive electron hops from the source to a trap and from the trap to the drain. The rates do not depend on the previous hops nor on time. The method allows to evaluate the electron current as well as the low frequency current noise at spin-dependent hopping. Our Monte Carlo approach resolves a controversy between theoretical results found in literature.
The financial support by the Austrian Federal Ministry for Digital and Economic Affairs and the National Foundation for Research, Technology and Development is gratefully acknowledged.
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