Empirical values of $\frac{E2}{M1}$ mixing ratios in even-even deformed nuclei are compared with the predictions of the interacting-boson-approximation (IBA) model. It is shown that the IBA results are equivalent to those obtained from a geometrical approach, and also lead to certain unique predictions concerning the relative magnitudes and signs of the $\delta \left(\frac{E2}{M1}\right)$ values. The application of the IBA $M1$ operator in other regions is also discussed.

• Received 28 October 1981

DOI:https://doi.org/10.1103/PhysRevLett.47.1819