  We demonstrate that the different magnetic states of a Mn12 molecule can be
distinguished in a two-probe transport experiment from a complete knowledge of
the current-voltage curve. Our results, obtained with state-of-the-art
non-equilibrium transport methods combined with density functional theory,
demonstrate that spin configuration-specific negative differential resistances
(NDRs) appear in the I-V curves. These originate from the interplay between
electron localization and the re-hybridization of the molecular levels in an
external electric field and allow the detection of the molecule's spin-state.
