Nuclear structure and phase transition of odd-odd Cu isotopes: A neutron-proton interacting boson-fermion-fermion model calculation

Low-lying energy states of the odd-odd (60-66)Cuisotopic chain are studied within the framework of interacting boson-fermion-fermion model (IBFFM-1) and the neutron-proton interacting boson-fermion-fermion model (IBFFM-2). The obtained results compare well with the available experimental data and IBFFM-1, which augment the reliability of the wave function and Hamiltonian applied within the IBFFM-2 model. The ground-state phase transitions in Cu odd-A and odd-odd nuclei are investigated. Some signs of shape-phase transitions are seen in odd-odd nuclei. The obtained results indicate that the spectra of these isotopes similar to Cu odd-A nuclei provide good examples of vibrational symmetry without any significant deformed gamma-unstable structure. So, well known properties in the odd mass nuclei persist also in the odd-odd mass system. The calculations reproduce this behavior. (C) 2020 Elsevier B.V. All rights reserved.