Prediction of two-dimensional materials with half-metallic Dirac cones: Ni2C18H12 and Co2C18H12

Here, we demonstrate via density functional theory that low-buckled two-dimensional (2D) Co2C18H12 lattice structure are spin-polarized while high-buckled 2D Co2C18H12 lattice structure being spin-unpolarized. Since the separated low-buckled and high-buckled states of Co2C18H12 can be viewed as two states of memory devices, transition between the two states would provide high efficiency and high sensitivity for device applications. More interestingly, we predicate that 2D Ni2C18H12 lattice structure and low-buckled 2D Co2C18H12 lattice structure possess amazing half-metallic Dirac point Fermi surfaces, i.e., owning Dirac points in one spin channel with Fermi level located exactly at the touching point and half-metallic simultaneously. This might lead to promising novel applications and shows an important way to extend the applications of 2D materials in spintronics devices.