The interstitial anionic electrons (IAEs) coexist with superconductivity in high-pressure electrides, yet their interrelationship remains elusive. Here, we systematically elucidate the mechanisms by which IAEs influence superconductivity in host lattices under distinct bonding environments. Through crystal-structure prediction and first-principles calculations, we identified two high-pressure electrides, $I4/mmm-\mathrm{L}{\mathrm{i}}_4\mathrm{Pd}$ and $P{2}_1/m-\mathrm{L}{\mathrm{i}}_6\mathrm{Pd}$. Their superconducting transition temperatures ($T_{\mathrm{c}}\mathrm{s}$) are 21 K at 130 GPa and 43 K at 150 GPa, respectively. Our calculations reveal that the electrons in the p-p hybrid orbitals formed by Li and Pd exhibit pronounced electron-phonon coupling, which is the key factor responsible for superconductivity in both electrides. Strikingly, in $I4/mmm-\mathrm{L}{\mathrm{i}}_4\mathrm{Pd}$, IAEs occupy these hybrid orbitals. Increasing pressure enhances their localization, which reduces the electronic density of states at $E_{\mathrm{F}}$ and thereby weakens the EPC. In contrast, IAEs in $P{2}_1/m-\mathrm{L}{\mathrm{i}}_6\mathrm{Pd}$ do not occupy p-p hybrid orbitals at the Fermi level. Instead, its superconductivity originates solely from delocalized electrons residing in the p-p hybrid orbitals, leading to a higher $T_{\mathrm{c}}$. Our results highlight the critical role of p-p hybridization in governing the superconductivity in Li-transition-metal compounds and demonstrate, from the perspective of orbital occupation, that IAEs occupying hybrid orbitals at the Fermi level are detrimental to superconductivity.

Close

PrevNext

View figure in article

• Electron-phonon coupling
• High-pressure studies
• Superconductivity
• Electrides
• Density functional calculations