Magnetic Multilayer Edges in Bernal-Stacked Hexagonal Boron Nitride

Abstract

Single-layer $h$-BN is known to have edges with unique magnetism, however, in the commonly fabricated multilayer ${\text{AA}}^{\prime }$-$h$-BN, edge relaxations occur that create interlayer bonds and eliminate the unpaired electrons at the edge. Recently, a robust method of growing the unconventional Bernal-stacked $h$-BN (AB-$h$-BN) has been reported. Here, we use theoretical approaches to investigate the nitrogen-terminated zigzag edges in AB-$h$-BN that can be formed in a controlled fashion using a high-energy electron beam. We find that these "open" edges remain intact in bilayer and multilayer AB-$h$-BN, enabling researchers potentially to investigate these edge states experimentally. We also investigate the thermodynamics of the spin configurations at the edge by constructing a lattice model that is based on parameters extracted from a set of first-principles calculations. We find that the edge spins in neighboring layers interact very weakly, resulting in a sequence of independent spin chains in multilayer samples. By solving this model using Monte Carlo simulations, we can determine nm-scale correlation lengths at liquid-N${}_2$ temperatures and lower. At low temperatures, these edges may be utilized in magnetoresistance and spintronics applications.