Electronic and magnetic properties of substituted BN sheets: A density functional theory study

Using density functional calculations, we investigate the geometries, electronic structures and magnetic properties of hexagonal BN sheets with 3d transition metal (TM) and nonmetal atoms embedded in three types of vacancies: V^B, V^N, and V^B+N. We show that some embedded configurations, except TM atoms in V^N vacancy, are stable in BN sheets and yield interesting phenomena. For instance, the band gaps and magnetic moments of BN sheets can be tuned depending on the embedded dopant species and vacancy type. In particular, embedment such as Cr in V^B+N, Co in V^B, and Ni in V^B leads to half-metallic BN sheets interesting for spin filter applications. From the investigation of Mn-chain (C_Mn) embedments, a regular 1D structure can be formed in BN sheets as an electron waveguide, a metal nanometre wire with a single atom thickness.