Proposal for a Dual Spin Filter Based on [VO(C3S4O)2]2-

Polynuclear magnetic molecules often present dense electronic transmission spectra with many overlapping conduction spin channels. Single-metal complexes display a sparser density of states, which in the presence of a fixed external magnetic field makes them interesting candidates for spin filtering. Here we perform a DFT study of a family of bis- and tris-dithiolate vanadium complexes sandwiched between Au(111) electrodes and demonstrate that [VO(C3S4O)(2)](2-) can behave as a dual spin filter. This means that an external electrical stimulus can switch between the selective transmission of spin-up and spin-down carriers. By using an electrostatic gate, we show that the onset for the spin-up conductance is at a voltage V-g = -0.51 V, but a small shift to V-g = -0.63 V is capable of switching to spin-down transport. For both cases, we estimate a large low-bias conductance (approximately 2 mu S at V-bias < 50 mV) with excellent spin selectivity (>99.5%). We conclude by commenting on the general molecular requirements for the chemical design of further examples of such spintronics components.