Two hydrogen-rich materials: H3S and LaH10, synthesized at megabar pressures have revolutionized the field of superconductivity by providing a first glimpse into the solution for the hundred-year-old problem of room-temperature superconductivity. The mechanism governing these exceptional superconductors is the conventional electron-phonon coupling.
This talk provides a brief historical overview of the theoretical predictions together with background on motivations and techniques that lead to the subsequent experimental confirmation.
Theoretical calculations using density-functional based structure-search methods combined with BCS-type models predicted a new class of dense, hydrogen-rich materials – superhydrides (MHx, with x > 6 and M selected rare earth elements) – with superconducting critical temperatures (Tc) in the vicinity of room-temperature at Mbar pressures. The existence of a series of these phases was subsequently confirmed experimentally, and techniques were developed for their syntheses and characterization, including measurements of structural and transport and magnetic properties, at megabar pressures.
Experimental results will be discussed on both sulfur and lanthanum hydrides together with possible strategies to optimize pressure and transition temperatures in conventional superconducting materials. The talk highlights the novel physics in hydrogen-rich materials at high densities, the success of ‘materials by design’ in the discovery and creation of new classes of superconductors with Tc’s at and above room temperature.