Room temperature superconductivity: State of the Art | Dr. Pablo Esquinazi

9 Mayo 2023 - Aula Magna - FAMAF Docentes

Seminario brindado por el Dr. Pablo Esquinazi.

Martes 9 de mayo (11 hs ) en el aula magna de FAMAF, el seminario será dictado en castellano.

In recent years a relatively large number of publications in journals of high-level citations (Nature, etc.) show that compounds with hydrogen under pressure could become superconducting up to room temperature. In my talk I am going to summarize the problems that exist with the published data, the recent "battle" about the interpretation of these results and the key issue several coauthors of those high-citation-index papers did not take into account. The main phenomenology that it is expected from inhomogeneous superconductors is in general that of granular superconductivity. For example: an anomalous field hysteresis in the magnetoresistance, or the possibility of producing a permanent current in the sample after decreasing an applied magnetic field to zero, as examples. Not all these features were fully demonstrated in compounds with hydrogen under pressure. However, they were published in the last 15 years on pure graphite samples. Several of these results will be summarized in the talk, indicating the existence of superconductivity with critical temperature around 350K or even above it, as recent reports from laboratories in France indicate. Theoretical work and experimental hints suggest that superconductivity is induced at certain two-dimensional stacking faults (interfaces), which most of highly oriented graphite samples in a certain proportion have.

El Dr Esquinazi es un reconocido Investigador en el área de la física del estado sólido cuenta con más de 340 papers en revistas indexadas internacionales teniendo más de 10.000 citaciones ( h-index > 40 (SCOPUS), h-index > 50 (Google Scholar) and i10-index > 200.

Sus principales contribuciones en el área son :

-Production of amorphous superconductors and the study of their superconducting properties (1980-1984) ; -First evidence for the existence of tunneling systems in high-temperature superconductors and the study of their acoustic properties at low temperatures (1987-1988); -Evidence for the existence of a vertical (magnetization axis) shift due to an exchange bias phenomenon (2011-2014) ;-Discovery of magnetic field dependence in the photoconductivity in magnetic ZnO due to defects (2011,2015) ;-Influence of the oxygen vacancies on the magnetic properties of Zn-ferrite (2011,2014);-Development of the physics of pinning of flux lines in vibrating superconductors (1986-1994) ;-Interpretation of several experimental studies based on thermally activated (de)pinning and vortex diffusion phenomenon in high-temperature superconductors (1989-1996) ;-First studies of acoustic properties of crystalline and amorphous solids down to 100 microkelvin; -Evidence for the existence of tunneling systems in polycrystalline metals (1992-2000); - First evidence for superconducting and ferromagnetic behavior of bulk graphite, beginning of the study of the phenomenon defect-induced magnetism in carbon-based and oxides systems (2000 Discovery of the semiconducting properties of the Bernal and rhombohedral lattice and the existence of superconductivity at interfaces of graphite; reinterpretation of several transport and magnetic properties of graphite published since 1940 (2008-2019); Discovery of magnetic order by proton irradiation in graphite (2003-2010).