Synthesis of Superconducting Beryllium Thin Film by Ion-Beam Sputtering

The superconductivity of beryllium films prepared by ion-beam-sputtering on substrates at room temperature originated in a metastable, highly disordered structure. The superconducting critical temperature (T c) increased up to 7.0 K when the film thickness increases up to 20 nm. When crystal particles of normal hcp phase were grown in films with thicknesses of more than 40 nm, the T c decreased. Incorporating oxygen into the film was helpful in making the film homogeneous by preventing hcp crystals from growing larger, but this tended to decrease T c.