title: Probing non-dipole allowed excitations in highly correlated materials with nanoscale resolution.
abstract: Here, we demonstrate that non-dipole allowed d-d excitations in NiO can be measured by electron energy loss spectroscopy (EELS) in transmission electron microscopes (TEM). Strong excitations from (3)A(2g) ground states to (3)T(1g) excited states are measured at 1.7 and 3 eV when transferred momentum are beyond 1.5 A(-1). We show that these d-d excitations can be collected with a nanometrical resolution in a dedicated scanning transmission electron microscope (STEM) by setting a good compromise between the convergence angle of the electron probe and the collected transferred momentum. This work opens new possibilities for the study of strongly correlated materials on a nanoscale.
authors: Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud, F-91405 Orsay, France. gloter@lps.u-psud.fr
authors: Alexandre
authors: A
authors: Gloter
authors: Ming-Wen
authors: MW
authors: Chu
authors: Mathieu
authors: M
authors: Kociak
authors: Cheng Hsuan
authors: CH
authors: Chen
authors: Christian
authors: C
authors: Colliex