  We investigate the electron transport properties of a model magnetic molecule
formed by two magnetic centers whose exchange coupling can be altered with a
longitudinal electric field. In general we find a negative differential
conductance at low temperatures originating from the different scattering
amplitudes of the singlet and triplet states. More interestingly, when the
molecule is strongly coupled to the leads and the potential drop at the
magnetic centers is only weakly dependent on the magnetic configuration, we
find that there is a critical voltage V_C at which the current becomes
independent of the temperature. This corresponds to a peak in the low
temperature current noise. In such limit we demonstrate that the quadratic
current fluctuations are proportional to the product between the conductance
fluctuations and the temperature.
