Evolution of superconductivity and charge order in pressurized RbV3Sb5

The kagome metals AV3Sb5 (A = K, Rb, Cs) under ambient pressure exhibit an unusual charge order, from which superconductivity emerges. In this work, by applying hydrostatic pressure using a liquid pressure medium and carrying out electrical resistance measurements for RbV3Sb5, we find the charge order becomes suppressed under a modest pressure p c (1.4 < p c < 1.6 GPa), while the superconducting transition temperature T c is maximized. T c is then gradually weakened with further increase of pressure and reaches a minimum around 14.3 GPa, before exhibiting another maximum around 22.8 GPa, signifying the presence of a second superconducting dome. Distinct behaviors in the normal state resistance are found to be associated with the second superconducting dome, similar to KV3Sb5. Our findings point to qualitatively similar temperature-pressure phase diagrams in KV3Sb5 and RbV3Sb5, and suggest a close link between the second superconducting dome and the high-pressure normal state resistance.

Interface structure of a YBa2Cu3O7−x/N/YBa2Cu3O7−x superconductor/normal metal/superconductor Josephson junction using YBa2Cu2.79Co0.21O7−x as the normal barrier N

Superconductor-normal-superconductor (SNS) edge junctions consisting of YBa2Cu3O7/YBa2Cu2.79Co0.21O7−x/YBa2Cu3O7 were fabricated on (001) YSZ substrates using laser deposition. In contrast to other SNS junctions, e.g., with La0.5Sr0.5CoO3, CaRuO3, or SrRuO3 as the barrier layer, these devices do not display an excess normal-state resistance. High-resolution and conventional transmission electron microscopy (TEM) techniques were employed to investigate the SN interface structure and possible interface defects. Results are compared to recent TEM investigations of CaRuO3 SNS junctions.