Quantum phase transitions in rotating nuclei

We extend the classical Landau theory for rotating nuclei and show that the backbending in 162Yb, that comes about as a result of the two-quasiparticle alignment, is identified with the second order phase transition. We found that the backbending in 156Dy, caused by the instability of $\gamma$-vibrations in the rotating frame, corresponds to the first order phase transition.