Instability of nuclear wobbling motion and tilted axis rotation

We study a possible correspondence between the softening of the wobbling mode and the "phase transition" of the one-dimensionally rotating mean field to a three-dimensionally rotating one by comparing the properties of the wobbling mode obtained by the one-dimensional cranking model + random phase approximation with the total routhian surface obtained by the three-dimensional tilted-axis cranking model. The potential surface for the observed wobbling mode excited on the triaxial superdeformed states in $^{163}$Lu is also analyzed.