Realizing bias-induced spin transition with high-spin MnII complexes at room temperature

Abstract

Spin crossover complexes in the ground state with a low-spin magnetic ion are usually used to realize electrically-induced spin transition in experiments. We propose that complexes in the ground state with a high-spin magnetic ion are also suitable for this purpose. Taking the molecule [Mn(terpy)₂]²⁺ as an example, our first-principles study shows that the transition from high spin to low spin can be achieved only by adding one electron to the molecule at 0, 300 and 370 K. We further show that such an electron addition can be implemented by integrating the molecule into a two-terminal molecular junction with a moderate bias voltage applied. Moreover, the spin transition related magnetoresistance ratio [R_ST = (I_LS − I_HS)/I_HS] can be up to 400. Therefore, one can easily build room-temperature molecular devices (e.g. molecular transistors and memory devices) working on the electrically-induced spin transition when using our proposed complexes. Note that our proposed complexes should feature a high-spin magnetic ion of 3d⁵ (3d⁴) in a nearly octahedral structure and several pyridine moieties directly coordinated to this magnetic ion, but are not limited to the molecule [Mn(terpy)₂]²⁺.