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

TL;DR

This study predicts that applying high pressure to YBa2Cu3O7 can induce a second superconducting dome by altering orbital hybridization and phase structure, offering insights into high-temperature superconductivity mechanisms.

Contribution

Using ab initio methods, the paper reveals pressure-induced phase transitions and orbital hybridization changes that support the existence of a second superconducting dome in YBa2Cu3O7.

Findings

Pressure induces a phase transition replacing antiferromagnetic order.

Strong hybridization of $d_{x^2-y^2}$ and $d_{z^2}$ orbitals observed.

Collapse of pseudogap phase linked to second dome emergence.

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.