SPIN CONFIGURATIONS AND QUASI-PARTICLE FRACTIONAL CHARGE OF FRACTIONAL QHE GROUND-STATES IN THE N=0 LANDAU-LEVEL

Spin configurations of fractional states v= p q in the N=0 Landau level are examined by in-situ rotation studies of an exceptionally high quality sample. The 2 3 and 4 3 parent states are found to be unpolarised at low B, as is the 8 5 daughter state (of the polarised 5 3 parent), and field-induced phase transitions for these states are observed. The validity of the probe σcxx=σxx ( 1 T=0) {difference between} ( e q)2/h of the quasiparticle fractional charge e*=± e q is confirmed by extensive integer QHE activation studies, from which a universal prefactor σcxx close to e2 h is identified. © 1990.