Buffer-layer-enhanced growth of a single-domain LaB6 (1 0 0) epitaxial thin film on a MgO (1 0 0) substrate via pulsed laser deposition

Epitaxial growth of LaB6 (1 0 0) thin films was examined on MgO (1 0 0) and sapphire (α-Al2O3) (0 0 0 1) substrates with insertion of a 2–3 nm-thick epitaxial SrB6 buffer layer by pulsed laser deposition in ultra-high vacuum. Reflection high-energy electron diffraction, X-ray diffraction, and the Raman scattering spectroscopy measurements proved that the heteroepitaxial structure of the LaB6 (1 0 0)/SrB6 (1 0 0)/MgO (1 0 0) substrate has a single-domain, while and that of the LaB6 (1 0 0)/SrB6 (1 0 0)/sapphire (0 0 0 1) substrate have three domains. LaB6 thin films grown without the buffer layer were not epitaxial; instead, they developed as polycrystalline films with a random in-plane configuration. The buffer layer greatly affected the initial growth of the LaB6 thin films. Epitaxial LaB6 thin films exhibited metallic behavior with almost constant resistivities in the temperature range 12–300 K. At room temperature, the resistivities of single-domain LaB6 (1 0 0) epitaxial thin films on MgO substrates were about 5 times smaller than those of the three-domain LaB6 (1 0 0) epitaxial thin films on the sapphire substrates.

► Epitaxial growth of LaB6 thin films was examined on MgO and sapphire substrates. ► Heteroepitaxial structure of the LaB6 films on MgO substrates has a single-domain. ► Heteroepitaxial structure of the LaB6 films on sapphire substrates has three domains. ► Buffer layer greatly affected the initial growth of the LaB6 thin films. ► LaB6 (1 0 0) epitaxial thin films exhibited metallic behavior.