Phonon enhancement of electronic order and negative isotope effect in the Hubbard-Holstein model on a square lattice
Phonon enhancement of electronic order and negative isotope effect in the Hubbard-Holstein model on a square lattice
In phonon mediated conventional $s$-wave superconductors, higher-frequency phonon (or smaller atomic mass) leads to a higher superconducting transition temperature, known as the isotope effect. However, in correlated systems, various competing electronic order (such as spin-density-wave, charge-density-wave, and unconventional superconductivity) arises and the effect of electron-phonon coupling on these orders is …