Boosted spintronic properties in triangular Si-based nanoflakes

Abstract

We investigate the magnetic properties of triangular silicene, silicon carbide, Si2BN, and their heterostructures using first principles calculations. Hydrogenation of surface Si atoms significantly enhances the net spin of silicene to 3n/2, n is the number of edge atoms, with perfect distribution only on the zigzag edges. The attached hydrogen prevents π-bonds formation between surface and edge Si-atoms, which provides all silicene edge atoms with unpaired p-orbital electrons to form half-filled states. Silicon carbide with C-/Si- edge atoms has ferromagnetic/antiferromagnetic ordering because of the formation of planer/edge-buckled structure; buckling at the edges arranges the topologically frustrated edge atoms in opposite directions making a net spin of 0zero. Stacking in heterostructures removes the magnetic ordering by forming interlayer π-bonds between edge atoms while twisting one of the layers may isolate some of edge atoms and retain the ferromagnetic state. All the considered flakes are diamagnetic materials with highest diamagnetism in silicene and its heterostructures. However, attaching iron oxide (Fe2O3) to the interactive Si-surface atoms transforms silicene to paramagnetic material, with positive net magnetic susceptibility. In addition to the improved magnetic properties, the electronic properties are also controllable. Thus, these flakes are promising candidates for performant semiconductor spintronics.