The nature of the $\gamma$ band is studied for the soft triaxial even-even Xe isotopes ${}^{122–128}\mathrm{Xe}$ employing the five-dimensional collective Hamiltonian based on relativistic density functional theory. The theoretical calculations successfully reproduce the experimental staggering parameters $S\left(I\right)$ of the $\gamma$ band as well as the intraband and interband $B\left(E2\right)$ values for the ground-state band and $\gamma$ band. Pronounced $\gamma$ softness is shown across the Xe isotopes. Additionally, the analyses of angular momentum geometry via spin coherent state maps reveal that the even-spin states of the $\gamma$ band show large amplitude collective motion along $\gamma$ direction, while the odd-spin states exhibit wobbling mode with respect to the medium axis.

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• Collective levels
• Nuclear structure & decays
• 90 ≤ A ≤ 149
• Collective models