The Magnetic Characteristics Of 5d Transition Metal Absorbed Graphyne:A First-principles Study

The graphene, a kind monolayer material, has attracted much attention to researchers due to its remarkable properties and vast application. Unlike the zero band gap characteristics of graphene, the graphyne with 0.52 eV band gap and the properties more like the traditional semiconductor, which we can more easy to modulate its band structure. Since the graphyne has broad application prospects in nano electronics and spintronics devices, it has attracted wide attention. To further expand its application, we have to controllably modulate its properties. One of the most effective approachers is transition metal(TM) absorbed. Previous studies show that the magnetic properties can be induced in 2D material by TM absorbing. To obtained larger magnetic anisotropy energy( MAE) is important in magnetic memory device. Magnetic atom absorbed on nonmagnetic substrate is a good way to achieve the goal. In present work, useing first-principles calculations, we have studied the magnetic properties, magnetic anisotropy energy and electronic structure of 5d transition metal absorbed on graphyne, the main conclusions are as follow:1. We have studied the modulation effect on the magnetic properties of graphyne trough single 5d TM(Hf, Ta, W, Re, Os and Ir) atoms adsorbed on it. Our calculations show that it is stable for single 5d TM absorbed on graphyne and it can induced the magnetic of the system except the Hf, The TM-graphyne system exhibit spin-polarized metal characteristics.2. The materials with large MAE show broad application prospect on magnetic device. The size and dimensional effect of two dimensional materials provide favorable conditions for obtaining large magnetic anisotropy. Thus, it is a potential approach to realize large MAE through 5d TM absorbed on graphyne. Our result show that when Re,Os and Ir absorbed on graphyne, their MAEs reach-59.91 me V, 17.81 me V and-28.88 meV, respectively. But the small MAE for Ta and W absorbed systems, their values are 3.97 meV and 7.17 me V, respectively. For Re and Ir absorbed systems their easy-axis along z orientation but other systems show in-plane easy-axis. We found that the MAE of the systems depend on the Hubbard U. Based on the U obtained by linear response theory, we study the evolution of the MAE with U changed from 0 to maximum(the calculated value). The m- resolved PDOS shows that interaction strengthen of the occupied and unoccupied near the Fermi level determined the value of MAE, the U will affect the interaction strengthen betwen occupied and unoccupied, by which influences the MAE of the systems.3. Based on the study of single 5d TM absorbed on graphyne, we further investigated the magnetic and electronic structures of 5d TM full-absorbed on the alkyne site of graphyne. We found that the Re full-absorbed system shows 2B? magnetic moment and exhibit half-metal originate from the Re d orbital. But for Os and Ir, the magnetic moment is 0B? and 0.06B?, respectivly.4. We calculated the MAE of 5d TM(Re and Ir) full-absorbed on graphyne's alkyne site. For the system of Re full-absorbed on graphyne, the MAE is-53.07 meV, only decreased about 7me V in comparsion with the single Re absorbed graphyne. But for Ir full-absorbed only shows 0.19 me V MAE, The large MAE of Re full-absorbed systems on graphyne's alkyne site derives from the strong interaction between occupied and unoccupied near the Fermi level, the same origination of occupied and unoccupied states(both of them come from |m|=2) produces easy-axis along the z orientation of the systems. In summary of our work show that Re absorbed graphyne is a potential material for magnetic memory device.