Anomalous behaviour of the 2$^+$ mixed-symmetry state in $^{94}$Zr

The low-spin structure of $^{94}$Zr has been studied with the (n,n$'$$\gamma$) reaction, and branching ratios, lifetimes, multipolarities and spin assignments were determined. The 2$^+_2 $ state at 1671.4 keV has been identified as the lowest mixed-symmetry state in $^{94}$Zr. The 752.5 keV transition from this state to the 2$^+_1$ level has a large B(M1) value of 0.33 (5) $\mu_N^2$, and the B(E2) of the transition to the ground state has an unusually large value of 8(1) W.u. The $M1$ transition strength is in agreement with IBM-2 predictions in the U(5) vibrational limit, whereas the large B(E2;2$^+_{1,MS} $$\rightarrow$0$^+_1$) value significantly exceeds the $E2$ strength predicted by the IBM-2. For the first time, the 2$^+_ {1,MS}$$\rightarrow$0$^+_1$ E2 transition is observed to have a larger E2 transition strength than the 2$^+_{1}$$\rightarrow$0 $^+_1$ decay.