Growth of epitaxial YB_6-x films with molecular beam epitaxy

Yttrium hexaboride (YB₆) is an s-wave superconductor with a critical temperature of around 8 K. While numerous previous studies of YB6 focused on the properties of bulk crystals, the synthesis of epitaxial YB_6-x thin films presents a new avenue to investigate the effects of surface termination, thickness, and strain in this system. In this work, we use molecular beam epitaxy (MBE) to deposit sub-40 nm thick YB_6-x films on semiconducting (001)-oriented Si substrates. We use ex-situ x-ray diffraction, atomic force microscope, and magnetotransport measurements to assess the effect of growth conditions on film properties and prospects for incorporating YB₆ into rare-earth hexaboride heterostructures.