过渡金属掺杂的扶手椅型氮化硼纳米带的磁电子学特性及力-磁耦合效应

Magneto-electronic properties and mechano-magnetic coupling effects in transition metal-doped armchair boron nitride nanoribbons

基于密度泛函理论的第一性原理计算方法,研究了多种过渡金属(TM)掺杂扶手椅型氮化硼纳米带(ABNNR-TM)的结构特点、磁电子特性及力-磁耦合效应.计算的结合能及分子动力学模拟表明ABNNRTM的几何结构是较稳定的,同时发现对于不同的TM掺杂,ABNNRs能表现出丰富的磁电子学特性,可以是双极化磁性半导体、一般磁性半导体、无磁半导体或无磁金属.双极化磁性半导体是一种重要的稀磁半导体材料,它在巨磁阻器件和自旋整流器件上有重要的应用.此外,力-磁偶合效应研究表明:ABNNR-TM的磁电子学特性对应力作用十分敏感,能实现无磁金属、无磁半导体、磁金属、磁半导体、双极化磁性半导体、半金属等之间的相变.特别是呈现的宽带隙半金属对于发展自旋电子器件有重要意义.这些结果表明:可以通过力学方法来调控ABNNR-TM的磁电子学特性.

Owing to the novel structure and rich electromagnetic properties, graphene shows very great promise in developing future nano-electronic devices and has thus attracted ever-increasing attention. Its isomorph-single layer, hexagonal boron-nitride （h-BN）, in which carbon atoms in graphene are replaced with alternating boron and nitrogen atoms in the sp2 lattice structure, has led to a new research boom in condensed matter physics and material science. Although an h-BN layer has a similar structure to graphene, it possesses a number of properties different from its carbon counterpart. In this work, the first-principles method based on density functional theory is used to study the structural stability, magneto-electronic properties and mechano-magnetic coupling effects for an armchair BN nanoribbon doped with different transition metals （ABNNR-TM）. The calculated binding energy and molecular dynamic stimulation suggest that these structures are stable. Meanwhile, the calculated results show that ABNNR-TM holds diverse magneto-electronic properties upon different TM doping. For example, they may be nonmagnetic metals, nonmagnetic semiconductors, magnetic metals, magnetic semiconductors, or bipolar magnetic semiconductors. In particular, the bipolar magnetic semiconductor is an important semiconducting material, which has promising applications in the fields of the giant magnetoresistance and the spin rectifying devices. Besides, the investigations on mechano-magnetic coupling effects indicate that magneto-electronic properties of ABNNR-TM are very sensitive to the stress, which can realize the phase transformation between the nonmagnetic metal, nonmagnetic semiconductor, magnetic metal, magnetic semiconductor, bipolar magnetic semiconductors, and half metal. Particularly, the obtained wide-gap half metal is of significance for developing novel spintronic devices. In short, this work demonstrates that it is possible to tune magneto-electronic properties of ABNNR-TM by mechanic method.