All-boron planar ferromagnetic structures: from clusters to monolayers.

Ferromagnetism in all-boron planar clusters is revealed based on high-throughput first-principles calculations. Magnetic boron clusters induced from p electrons have been confirmed with large spins, e.g., S = 3 in a B34 cluster, which can be assembled to construct all-boron ferromagnetic monolayers. Notably, the ferromagnetic semiconductors of boron monolayers can be designed with the hybridization of a nonmagnetic B36 cluster in experimental synthesis. The ferromagnetism-paramagnetism transition and semiconductor-metal transition in these boron nanostructures will occur around 500 K according to ab initio molecular dynamics simulation, indicating the potential applications in nano-devices at room temperature. The coexisting ferromagnetic and semiconducting properties in boron monolayers are attributed to the unique multicenter bonds together with the modulation of structural symmetry, which might be worth experimental attempts in the future.