Spin configurations and quasiparticle fractional charge of fractional-quantum-Hall-effect ground states in the<i>N=0</i>Landau level

Abstract

Spin configurations of fractions z&lt;\ensuremath{\nu}&lt;2 are examined by angular and n-dependent activation studies. Energy gaps \ensuremath{\Delta}(\ensuremath{\theta}) and intercepts ${\ensuremath{\sigma}}_{\mathrm{xx}}^{c}$(\ensuremath{\theta}) that probe the quasiparticle charge ${e}^{\mathrm{*}}$ quantify a dramatic difference between (4/3 and (5/3 states consistent with assignments (4/3\ensuremath{\uparrow}\ensuremath{\downarrow}, and (5/3\ensuremath{\uparrow}\ensuremath{\uparrow} (\ensuremath{\uparrow}\ensuremath{\downarrow},\ensuremath{\uparrow}\ensuremath{\uparrow}=zero, maximum polarization). A field-induced phase transition $_{3}^{4}\ensuremath{\rightarrow}_{3}^{4}$ (partial polarization) in which ${e}^{\mathrm{*}}$ changes from e/3 to e/5 is mapped out. The (7/5 state formed from e/3 quasiparticles is destroyed at the (4/3 transition. High-order assignments $_{5}^{7}$(\ensuremath{\uparrow}\ensuremath{\uparrow} or \ensuremath{\downarrow}), $_{5}^{8}$ \ensuremath{\uparrow}\ensuremath{\downarrow}, $_{7}^{10}$ \ensuremath{\uparrow}\ensuremath{\downarrow}, and $_{7}^{11}\mathrm{\ensuremath{\uparrow}}$ are consistent with experiment.