Impurity effects of $\mathrm{\Lambda }$ particle on the 2$\alpha$ cluster states of ${}^9$Be and ${}^{10}$Be

The low-lying structure of ${}_{\mathrm{\Lambda }}^{10}$Be and ${}_{\mathrm{\Lambda }}^{11}$Be are investigated within the framework of the antisymmetrized molecular dynamics. We focus on the modifications of the excitation spectra and dynamical changes of the 2$\alpha$ cluster structure caused by a $\mathrm{\Lambda }$ particle as an impurity in these hypernuclei. It is found that the excitation energies of well-pronounced cluster states are largely shifted up by the addition of a $\mathrm{\Lambda }$ particle. Furthermore, we also find that the 2$\alpha$ cluster structure is significantly changed in the excited states, whereas it is almost unchanged in the ground states.