First Principles Study on the Magnetism of Rectangular Nanosilicenes

We present first-principle calculations on the magnetism in finite rectangular nanosilicenes (RNSs). An antiferromagnetic (AFM) state at two zigzag edges is found when the RNSs approach a critical size. This AFM state originates from the localized p_z orbits of Si atoms at the edges, similar to those in the infinitely long zigzag-edged silicon nanoribbons. The smallest RNS that can maintain the AFM phase as the ground state is identified. It is also found that aluminum dopants can regulate the distribution of the spin density and the energy difference between AFM and FM states.