Toward Ambient Superconductivity*

Superconductivity in the vicinity of room temperature has the potential to revolutionize both numerous technologies and our understanding of condensed matter. Zero electrical resistance and expulsion of magnetic field below critical temperature are critical tests of superconductivity. Since our group's disocovery of near-room temperature superconductivity in lanthanum superhydride at megabar pressures, a growing number of groups are reporting reproducible evidence for superconductivity at comparable temperatures in this and related hydrogen-rich materials under pressure.  Recently reported evidence for superconductivity near ambient P-T conditions in nitrogen-doped lutetium hydride is promising but controversial. Our group has conducted electrical resistance and magnetic susceptibility measurements, together with other characterization experiments, on Lu-N-H materials synthesized in different ways. The results confirm the remarkable properties of selected phases of these materials as well as the difficulty of their synthesis. First-principles DFT, DFT+U, and other simulations provide important insights into the behavior of these materials.