Jun-Jie Zhang

Direct imaging of the Ni $e_g$ hole orbitals in the bilayer nickelate La$_2$SmNi$_2$O$_7$

Models of unconventional superconductivity in cuprates and nickelates depend sensitively on the distribution of valence electrons among the $d$ orbitals. But accurately determining the orbital electron or hole occupations in these systems remains a difficult and unresolved task. Here, using $s$-core-level non-resonant...