물리학과

Superconductivity epitomizes the macroscopic quantum phenomena in the strongly correlated electron systems. The classical Bardeen-Cooper-Schrieffer (BCS) theory predicts that materials with high-phonon frequencies and strong electron-phonon coupling may induce superconductivity at elevated temperatures, close to the water freezing point. Even though metallic hydrogen, the first element in the periodic table, was proposed to become superconducting at room temperature, it has yet to be confirmed partly because the critical pressure required for its metallization has been too high to be achieved in the lab. Nevertheless, theory has predicted that metallic hydrides with crystalline structure similar to that of metallic hydrogen could be produced at an amenable pressure in the lab because of the ‘precompression’ enabled by the incorporation of appropriate constituent atoms, thereby providing an opportunity to test the scenario of room temperature superconductors (RTSCs). Indeed, the last decade has witnessed experimental breakthroughs in the study of RTSCs, i.e. high-T_c of 203 and 260 K was achieved in hydrogen-based materials (hydrides) SH₃ and LaH₁₀ systems, respectively. In October of 2020, remarkably, zero electrical resistance was recorded at 285 K in the ternary compound consisting of carbon, sulfur, and hydrogen, opening a new chapter in the study of RTSCs. In this colloquium, I’ll discuss superconductivity emergent in superhydries in comparison with other high-Tc superconductors.