Ultrathin boron nanoribbons: stability, conductivity, and edge magnetism

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: compacts-type ribbons built from triangular and square motifs, andsh-type ribbons containing larger polygonal voids. Thes-type members exhibit the highest binding energies and electrical conductivities, while selectedsh-type structures display distinctive electronic features, including a Dirac-like band crossing. Most BNRs are metallic, buts₄develops a gap due to quantum confinement ands₈becomes semiconducting only in its antiferromagnetic (AFM) ground state. The calculations further identify AFM ordering ins₈as robust andsh₃as weaker, both arising from edgepstates 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.