One-dimensional transition metal dihalide nanowires as robust bipolar magnetic semiconductors†
One-dimensional (1D) materials with robust ferromagnetic ground states are difficult to achieve but provide a significant platform for potential spintronic device applications in future. Herein, a new family of 1D transition metal dihalide (TMCl2; where TM = Cu, Co, Cr) nanowires are proposed by using first-principles calculations. Their dynamic stability is ensured by Born–Oppenheimer molecular dynamics simulations. The electronic structures demonstrate that both CoCl2 and CuCl2 nanowires are promising bipolar magnetic semiconductors (BMSs) and can be converted into 1D half-metal materials by a small amount of carrier doping. The CrCl2 nanowire is an antiferromagnetic semiconductor (AFS). The formation of a BMS is attributed to the superexchange coupling between the Co/Cu atoms through the 3p orbitals in the Cl atoms. By using Monte Carlo simulations, we found that the CoCl2 nanowire has a Curie point of 6 K, while the CuCl2 nanowire has a corresponding Curie point of 14 K. Our results allow us to put forward a strategy to realize 1D BMSs and to design low-dimensional AF spintronic devices.