Modulation of the octahedral structure and potential superconductivity of La3Ni2O7 through strain engineering

Abstract

The recent transport measurements of La₃Ni₂O₇ uncovered a “right-triangle” shape of the superconducting dome in the pressure-temperature (P-T) phase diagram. Motivated by this, we perform theoretical first-principles studies of La₃Ni₂O₇ with the pressure ranging from 0 to 100 GPa. Notably, we reveal a pressure dependence of the \(\text{Ni-}d_{\,z^{2}}\) electron density at the Fermi energy (\(n_{z}^{E_{\rm{F}}}\)) that highly coincides with such shape. On this basis, we further explore the electronic structure under uniaxial stress. By tracking the stress response of \(n_{z}^{E_{\rm{F}}}\), we propose that superconductivity can be achieved by applying only ⋃2 GPa of compression along the c axis. The idea is further exemplified from the perspectives of lattice distortion, band structure, Fermi surface and superconducting phase coherence. We also discuss the possible charge modulation under the stress and provide an insight into the relation between \(n_{z}^{E_{\rm{F}}}\) and the superconducting T_c in La₃Ni₂O₇ system. Our study provides new routes to the search of high-T_c superconductors in future experiments.