Controlling spin off state by gas molecules adsorption on metal-phthalocyanine molecular junctions and its possibility of gas sensor

Employing Green's function (GF) technique in combination with spin-polarized density functional theory (DFT), we study the electronic structure and magnetic properties of metal phthalocyanine (MPc) (M = Mn, Fe, Co, Ni, Cu, Zn) with or without four different gas molecules (NO, CO, O-2 and NO2) adsorbing on the M atom of MPc molecule. The corresponding stable adsorption structural configurations and transport properties of MPc molecular junctions are also investigated. Our results indicate that the magnetic moment of MPc for M = Mn, Fe and Co can be modified by the specific gas molecule adsorption, which is mainly ascribed to competitive relation of HOMO-LUMO Gap and Hund's rules. However, for M = Ni, Cu and Zn, it is difficult to detect gas molecule because the interaction of M atom and these gases is most of weak van der Waals interaction. Remarkably, the spin of MPc molecule can be switched to a magnetic off state by specific gas absorption, giving rise to a potential application on controllable spintronic devices. In addition, CO, NO, O-2 and NO2 gas molecules can be detected selectively by measuring spin filter efficiency of these MPc molecular junctions. On the basis of our results, MPc (M = Mn, Fe, Co) molecular junctions can be considered as a promising nanosensor device to detect individual gas molecules. (C) 2018 Elsevier B.V. All rights reserved.