[en] The cranked modified oscillator potential is used to study the nuclei ^172-180₇₂Hf at very high angular momenta. All these isotopes are found to 'rotate around the prolate symmetry axis' for spin values I=15-40h/2π. In this region of spin one then looks for prolate yrast traps. The pairing interaction with an approximative particle number projection as well as the hexadecapole degree of freedom are taken into account. The calculated traps agree fairly well with experiments. Additional traps are predicted, the highest at spin 39h/2π. (Auth.)