Metal hydrides: Epitaxial growth and electronic properties

Reports of superconductivity at temperatures above 200 K in high-pressure hydrogen sulfide (H₂S) had generated great interest in metal hydrides and their physical properties. For the progress in both fundamental understanding and device application of metal hydrides, studies using single crystals or epitaxial thin films are essential. However, to date, a few metal hydride single crystals and epitaxial thin films have been fabricated, and both fundamental and applied research on these materials remain elusive compared with oxides and nitrides. This article reviews the recent body of work that aims to establish a metal-hydride epitaxial thin film synthesis technology, and to search for new metal-hydride functionalities; it focuses on the epitaxial growth and properties of metal hydrides.