Triaxial rotation-axis flip triggered by an isoscalar np pair
We show that the rotation axis of a triaxial nucleus may flip from the intermediate axis (γ=-30) to the smallest axis (γ=+30) due to the polarization by an aligned T=0np pair. The example we discuss is the triaxial N=Z nucleus Ge64 where the isoscalar π(g9/2)- ν(g9/2) pair aligns to iπ=9+ in As66 and flips the rotation from γ≈-30 to γ≈30. Calculations are performed in the spherical shell model as