Gap Switching in Metal-Organic Coordination Chains

We predict two switchable one-dimensional (1D) spin-polarized semiconductors based on metal-organic coordination chains constructed out of Fe, V, and zwitterionic quinone (ZQ) molecules using first-principle density functional theoretical analysis. The Fe-ZQ coordination chain can be converted from a semiconductor to a half-metal when oxidized by chlorine (Cl). Upon chlorination, the magnetic moment of the Fe-ZQ is increased from 4 mu(B) to 5 mu(B), per iron atom. In addition, the bimetallic (Fe-ZQ-V-ZQ) ferromagnetic semiconducting coordination chain with a very small energy gap of only 90 meV can be converted to an antiferromagnetic semiconductor with a large gap of more than 1 eV when oxidized by chlorine. Its magnetic moment is found to be 8 mu(B) per heterobimetallic unit (Fe and V) after chlorination, and 7 mu(B) without chlorine. These unique properties, namely a switchable or reversible electronic and magnetic characteristics with a transition between different semiconducting states, make these coordination chains to be highly promising candidates for specific applications as multi-functional switch in nanoelectronics and spintronics.