Effects of magnetic field and transverse anisotropy on full counting statistics in single-molecule magnet

Hai-Bin Xue, Y. -H. Nie, Z. -J. Li, J. -Q. Liang

Published 2010-11-25, updated 2011-04-20Version 2

We have theoretically studied the full counting statistics of electron transport through a single-molecule magnet (SMM) with an arbitrary angle between the applied magnetic field and the SMM's easy axis above the sequential tunneling threshold, since the angle $\theta$ cannot be controlled in present-day SMM experiments. In the absence of the small transverse anisotropy, when the coupling of the SMM with the incident-electrode is stronger than that with the outgoing-electrode, i.e., $\Gamma_{L}/\Gamma_{R}\gg1$, the maximum peak of shot noise first increases and then decreases with increasing $\theta$ from 0 to $0.5\pi$. In particular, the shot noise can reach up to super-Poissonian value from sub-Poissonian value when considering the small transverse anisotropy. For $\Gamma_{L}/\Gamma_{R}\ll1$, the maximum peaks of the shot noise and skewness can be reduced from a super-Poissonian to a sub-Poissonian value with increasing $\theta$ from 0 to $0.5\pi$; the super-Poissonian behavior of the skewness is more sensitive to the small $\theta$ than shot noise, which is suppressed when taking into account the small transverse anisotropy. These characteristics of shot noise can be qualitatively attributed to the competition between the fast and slow transport channels. The predictions regarding of the $\theta$-dependence of high order current cumulants are very interesting for a better understanding electron transport through SMM, and will allow for experimental tests in the near future.