Condensed Matter Seminar: Room temperature superconductivity: state of the art

In recent years, a relatively large number of publications in high-level citations journals reported that compounds with hydrogen under pressure could become superconducting to room temperature. I am going to summarize some of those results, the problems that exist with the published data (some blockbuster results were indeed faked) and their interpretation. One key issue several authors of those high-citation-index papers did not take into account is granular superconductivity, a phenomenon expected for inhomogeneous superconductors. For example, anomalous field hysteresis in the magnetoresistance, or remanent states due to macroscopic permanent currents in the sample after decreasing a magnetic field to zero. These features were not yet found or fully clarified in hydrogen compounds under pressure and there are still controversial problems nowadays. On the other hand, several of these features were published in the last ~50 years in pure graphite samples. Some of these results will be summarized in the talk, indicating the existence of superconductivity with critical temperatures. Theoretical work and experimental results suggest that superconductivity in graphite is located at certain two-dimensional stacking faults or interfaces, most of oriented graphite samples have.