Shape transitions in proton-neutron systems

We explore the possibility of shape transitions in proton-neutron systems driven by deformation differences between proton and neutron fluids. Within the framework of the proton-neutron interacting boson model, we show that such dynamic shape transitions cannot occur in well deformed nuclei but are a possibility in transitional nuclei. Likely candidates in the Os-Pt isotopes are discussed and predictions of the model are compared with the existing data.