碳和氧掺杂紫磷烯作为双极磁性半导体材料的理论预测

Theoretical prediction of C-and O-doped Hittorf's violet phosphorene as bipolar magnetic semiconductor material

紫磷烯是一种结构稳定且具有优异光电特性的新型二维材料,研究掺杂效应有助于理解其物理本质,对进一步开发纳米电子器件具有重要意义.本文采用基于密度泛函理论的第一性原理方法,研究了非金属元素B,C,N,O掺杂单层紫磷烯的电磁性质.计算结果表明,B和N掺杂之后没有产生磁性,体系依旧表现为非磁性半导体;而C和O掺杂导致体系发生自旋劈裂,紫磷烯由非磁性半导体转变成为双极磁性半导体,其自旋密度主要分布在磷原子和间隙区域内而非杂原子上.电场调控氧掺杂紫磷烯可使其载流子的自旋极化方向发生反转,当施加一定大小的正向或反向的静电场时,能带色散程度变强,氧掺杂紫磷烯转变成100%自旋极化向下或向上的单自旋半金属磁体.基于氧掺杂紫磷烯材料设计的场效应自旋滤通器可利用改变门电压方向的方法实现电流自旋极化方向的反转,表明氧掺杂紫磷烯有望成为二维自旋场效应晶体管、双极磁性自旋电子学器件、双通道场效应自旋滤通器以及场效应自旋阀的理想候选材料.

Hittorf's violet phosphorene is a novel two-dimensional material with stable structure and excellent optoelectronic properties.Studying the doping effect helps to understand its physical essence and is of great significance in further developing nanoelectronic devices.In this paper,the first-principles method based on density functional theory is used to study the electromagnetic properties of the non-metallic element B-,C-,N-,and O-doped single-layer violet phosphene.The results show that there is no magnetism after having doped boron and nitrogen,and the system still behaves as a nonmagnetic semiconductor,while carbon doping and oxygen doping cause spin splitting,and the violet phosphorene transforms from a nonmagnetic semiconductor to a bipolar magnetic semiconductor,and its spin density is mainly distributed in the P atom and gap region,rather than on the impurity.The direction of spin polarization of its carrier can be reversed by adjusting the electric field of O-doped violet phosphorene.When a certain size of forward or reverse electrostatic field is applied,the band dispersion becomes stronger,and the O-doped violet phosphorene transforms into a halfmetallic magnet with 100% downward or upward spin polarization at the Fermi level.The field effect spin filter based on O-doped violet phosphorene can reverse the direction of spin-polarized current by changing the direction of the gate voltage.This study shows that O-doped violet phosphorene is expected to be an ideal candidate material for two-dimensional spin field-effect transistors,bipolar magnetic spintronic devices,dual channel field effect spin filters,and field-effect spin valves.