Explanation of an unexpected occurrence of fractional quantum Hall effect states in monolayer graphene

Abstract

Recent experiment reveals the appearance of incompressible fractional quantum Hall effect states in monolayer graphene at and , substituting the compressible Hall metal states at these fillings in the lowest Landau level in a narrow magnetic field window depending on the sample parameters. Simultaneously, none such behavior has been observed either for or , . We propose an explanation of these observations in terms of homotopy of monolayer graphene in consistence with a general theory of correlated states in planar Hall systems.