Half-Metals and Weyl Nodal Line Semimetals in Two-Dimensional Phthalocyanine-Based Metal Organic Frameworks with Ni–Fe Dual Metals

Abstract

Two-dimensional organic ferromagnetic half-metals and Weyl semimetals are desirable for nanoscale spintronic and electronic devices. However, two-dimensional half-metals and Weyl semimetals are sensitive to doping and strain, which hinder their further applications. Here, the electronic structure and magnetic properties of two-dimensional nickel phthalocyanine (NiPc)-based metal–organic frameworks are studied by first-principles calculations. NiPc linked by square-planar Fe–O4 (NiPc–Fe2) exhibits in-plane ferromagnetic half-metal properties with a large band gap and high Curie temperature. NiPc–Ni2 and NiPc–NiFe exhibit in-plane ferromagnetic half-metal properties with tunable band gaps and abundant electronic transitions by applying biaxial strain and charge doping. NiPc–Ni2 and NiPc–NiFe also exhibit Weyl semimetal properties with two closed nodal lines and one nodal line near the Fermi level, which shift toward the Fermi level under charge doping. When spin–orbit coupling is taken into account, nodal lines will open small gaps. These results enrich the two-dimensional magnetic half-metals and semimetals, which have potential applications in spintronic devices.