Electronic and transport properties of Fe-based spin crossover complexes from first principles

Using calculations from first principles, we studied the electronic and transport properties of the Fe(II) spin crossover (SCO) compound Fe[H$_2$B(pz)$_2$]$_2$(bpy). The magnetic transition has been imposed by constrained magnetization calculations and the computed electronic structure agrees with available experimental data. The unique bilayer configuration achievable by vacuum evaporation on Au(111) in experiments, is modeled by a $\pi$-stacking dimer structure that is used for the interpretation of STM and transport data. Our results explain the meandering spinodal decomposition of the spin domains of the bilayer films and the conductive properties of the system. In particular, we found the high-spin configuration to be more conductive than the low-spin case, in agreement with experimental measurements of corresponding currents through disordered thin films. The spin-switchable electronic transport properties of this kind of Fe(II) SCO compound systems provide viable proofs for future switchable molecular spintronic devices and applications.