Ultrathin boron nanoribbons: stability, conductivity, and edge magnetism

Abstract We report a systematic density functional theory study of ultrathin boron nanoribbons (BNRs), revealing a rich interplay between structural stability, electronic transport, and magnetism. Two distinct families are considered: compact s -type ribbons built from triangular and square motifs, and sh -type ribbons containing larger polygonal voids. The s -type members exhibit the highest binding energies and electrical conductivities, while selected sh -type structures display distinctive electronic features, including a Dirac-like band crossing. Most BNRs are metallic, but s ₄ develops a gap due to quantum confinement and s ₈ becomes semiconducting only in its antiferromagnetic (AFM) ground state. The calculations further identify AFM ordering in s ₈ as robust and sh ₃ as weaker, both arising from edge p states in analogy to zigzag graphene nanoribbons. Together, these results demonstrate that nanoscale geometry and edge topology decisively tune the properties of BNRs, establishing them as a versatile platform for next-generation nanoelectronic and spintronic devices.