Alexei Bagrets, Stefan Schmaus, Ali Jaafar, Detlef Kramczynski, Toyo Kazu Yamada, Mebarek Alouani, Wulf Wulfhekel and Ferdinand Evers

Nano Letters 12, 5131–5136 (2012)

The magnetoresistance of a hydrogen-phthalocyanine molecule placed on an antiferromagnetic Mn(001) surface and contacted by a ferromagnetic Fe electrode is investigated using density functional theory based transport calculations and low-temperature scanning tunneling microscopy. A large and negative magnetoresistance ratio of 50% is observed in combination with a high conductance. The effect originates from a lowest unoccupied molecular orbital (LUMO) doublet placed almost in resonance with the Fermi energy. As a consequence, irrespective of the mutual alignment of magnetizations, electron transport is always dominated by resonant transmission of Mn-majority charge carries going through LUMO levels.