Abstract : Shape coexistence at the Z=40 and/or N=40 are examples of interplay between macroscopical and
microscopical effects in nuclear matter leading to the competition between spherical normal state
and intruder deformed configurations. How the nuclei change drastically its shape when adding or
removing one or two pairs of nucleon remains an open subject in nuclear structure. Experimentally,
the development of radioactive beams facilities and state of the art detections systems opened new
avenues in the study of shape coexistence. In this presentation, the systematic study of shape
coexistence in neutron deficient Se and Kr isotopes, neutron rich Sr and Zr and neutron rich Fe and
Ni isotopes below 68Ni will be discussed from both experimental and theoretical perspectives.
