Thin film synthesis of rare earth and actinide nitrides using molecular beam epitaxy

Lanthanide- and actinide-based nitride compounds are an understudied group of materials compared to their oxide counterparts, which provide new avenues for nuclear reactor designs. Their 4f and 5f electron shell gives rise to a variety of interesting physics such as magnetism and unconventional superconductivity. [1] Samarium nitride (SmN) has been recently identified as a material where ferromagnetic order and potential p-type superconductivity coexist.

High-quality thin film samples are the ideal stage to study physical properties with high sensibility to defects, impurities, and structural distortions. We will present results on the growth conditions in a molecular beam epitaxy chamber of pure and doped SmN, and its electronic transport properties as a function of temperature and magnetic field. Similarities with CeN and UN thin films are also explored. The presence of SmN(111) peaks on (001) substrates indicates an orientation-preference for some material systems. The electrical resistivity and magnetic susceptibility studies have shown a range of magnetic behaviors, including paramagnetic and ferromagnetic. With a potential superconductive transition around ~10 K, SmN and its doping effects on crystal structure and electronic properties are characterized.

[1] Vallejo, K. D., Kabir, F., Poudel, N., Marianetti, C. A., Hurley, D. H., Simmonds, P. J., ... & Gofryk, K. (2022). Advances in actinide thin films: synthesis, properties, and future directions. Reports on Progress in Physics, 85(12), 123101.