A first-principles study on the electronic structure of one-dimensional [TM(Bz)]∞ polymer (TM= Y, Zr, Nb, Mo, and Tc)

A systematic density functional theory (DFT) study has been performed to investigate the electronic and magnetic properties of one-dimensional sandwich polymers constructed with benzene (Bz) and the second-row transition metal (TM = Y, Zr, Nb, Mo, and Tc). Within the framework of generalized gradient approximation (GGA), [Tc(Bz)]_∞ is a ferromagnetic half-metal, and [Nb(Bz)]_∞ is a ferromagnetic metal. With the on-site Coulomb interaction for 4d TM atoms being taken into account, [Tc(Bz)]_∞ keeps a robust half-metallic behavior, while [Nb(Bz)]_∞ becomes a spin-selective semiconductor. The stability of the half-metallic [Tc(Bz)]_∞ polymer is discussed based on magnetic anisotropy energy (MAE). Compared with 0.1 meV per metal atom in [Mn(Bz)]_∞, the calculated MAE for [Tc(Bz)]_∞ is 2.3 meV per metal atom. Such a significantly larger MAE suggests that Tc(Bz)]_∞ is practically more promising than its first-row TM equivalent.