Electron correlations in a partially filled first excited Landau level

The form of electron correlations in a partially filled degenerate Landau level (LL) is related to the behavior of the anharmonic part of the interaction pseudopotential. Unlike in the lowest LL, the pseudopotential in the first excited LL is harmonic at short range. As a result, the incompressible states in this LL have different correlations, occur at different filling factors,, and cannot be described by a composite fermion model. The series of Laughlin-correlated states of electron pairs is proposed at v = 2 + 2/(q(2) + 2) with integer q(2). It includes Moore-Read v = 5/2 state and the v = 7/3 state. Despite coincidence of the values of v, the latter state has different correlations than Laughlin state of single electrons at v = 1/3 and, in finite systems, occurs at a different LL degeneracy (flux). (C) 2002 Elsevier Science B.V. All rights reserved.