Proposal for a dual spin filter based on [VO(C₃S₄O)₂]²⁻

Polynuclear magnetic molecules often present dense 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(C$_3$S$_4$O)$_2$]$^{2-}$ can behave as a dual spin filter. This means that an external stimulus can switch between the selective transmission of spin-up and spin-down carriers. By using an electrostatic gate as external stimulus 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 activating spin-down transport. For both cases, we estimate a large low-bias conductance (approx. 2 {\mu}S at Vbias < 50 mV) with excellent spin selectivity (> 99.5%). We conclude by commenting on the general molecular requirements for the chemical design of further such spintronics components.