A Study of Reentrant Integer Quantum Hall States in High Landau Levels*

Reentrant integer quantum Hall states are widely thought to be realizations of the so called electronic bubble phases, some of the most intricate electron solids forming in the two-dimensional electron gas. According to the predictions of the Hartree-Fock theory, different types of bubble phases may exist, as distinguished by the number of electrons per bubble. So far, in the third and higher Landau levels four reentrant integer quantum Hall states were seen. Here we report the observation of eight reentrant integer quantum Hall states developing in the fourth Landau level. Properties of these reentrant states will be discussed. Our observation highlights the development of correlated phases of increasing complexity in improved samples and support the bubble interpretation of the reentrant integer quantum Hall states.