Hydrogen ion implantation in lanthanum thin films for ambient pressure hydride formation

Near room temperature superconductivity of metal hydrides has been demonstrated experimentally at high pressures (>100 GPa). It is desirable to decrease the formation and stability pressure while retaining a superconducting hydride phase. We implanted lanthanum thin films with various doses of hydrogen ions at ambient pressure and examined the effect of superconductivity. The critical temperature decreased from 4.6 K to 3.2 K with broader superconducting transitions. Transmission electron microscopy showed increased substrate damage with increased ion dose and confirmed their granular structure. Although the superconducting hydride phase requires a higher H⁺ dose than measured here, we have successfully demonstrated that ion implantation at ambient pressure is a feasible technique for lanthanum hydride formation.