Modulating hybrid interface states in magnetic molecular junctions by molecular geometrical torsion

The hybrid interface states and their dominated spin-dependent transport in a biphenyl magnetic molecular junction are investigated theoretically in the presence of molecular geometrical torsion. The results reveal a different response of the hybrid interface states relative to the molecular orbitals as the change of torsion angle between the two phenyl rings, where the projected density of states of the hybrid interface states is hardly disturbed while an obvious shift occurs for the molecular orbitals. The further transport calculation demonstrates that the spin-dependent current contributed by the hybrid interface states is suppressed by the torsion angle with a relation of cosine square of the torsion angle, which is consistent with that in nonmagnetic molecular junctions without obvious hybrid interface states. However, the tunneling magnetoresistance (TMR) of the junction can be enhanced by the torsion angle at high bias voltage. The dependence of the TMR on the torsion angle relies on the bias voltage and detailed situation of the hybrid interface state, which may be achieved by changing the anchoring group. This work indicates that one can modulate the current and TMR of magnetic molecular junctions by manipulating the conductance of hybrid interface states via the molecular conformation, which deserves further verification in experiments.