Second Dome of Superconductivity in YBa${}_2$Cu${}_3$O${}_7$ at High Pressure

Abstract

Evidence is growing that a second dome of high-$T_{\mathrm{c}}$ superconductivity can be accessed in the cuprates by increasing the doping beyond the first dome. Here we use \emph{ab initio} methods without invoking any free parameters, such as the Hubbard $U$, to reveal that pressure could turn YBa${}_2$Cu${}_3$O${}_7$ into an ideal candidate for second-dome-superconductivity, displaying the predicted signature of strongly hybridized $d_{x^2-y^2}$ and $d_{z^2}$ orbitals. Notably, pressure is found to induce a phase transition replacing the antiferromagnetic phases with an orbitally-degenerate $d$--$d$ phase. Our study suggests that the origin of the second dome is correlated with the oxygen-hole fraction in the CuO${}_2$ planes and the collapse of the pseudogap phase.

7 pages, 4 figures