M1 excitation in Sm isotopes and the proton-neutron sdg interacting boson model.

The magnetic-dipole scissors mode in spherical to deformed Sm isotopes is studied in terms of the proton-neutron {ital sdg} interacting boson model, providing a good agreement with recent experiment by Ziegler {ital et} {ital al}. The present calculation correctly reproduces the increase of {ital M}1 excitation strength in going from spherical to deformed nuclei. It is suggested that there may be 1{sup +} states which do not correspond to the scissors mode but absorb certain {ital M}1 strength from the ground state.