Nuclear spin-orientation dependence of magnetoconductance: a new method for measuring the spin of charged excitations in the quantum Hall effect

A new method for measuring the spin of the electrically charged ground-stat e excitations in the quantum Hall effect is proposed and demonstrated for t he first time for GaAs/AlGaAs multiquantum wells. The method is based on th e nuclear spin-orientation dependence of the two-dimensional direct-current conductivity in the quantum Hall regime due to the nuclear hyperfine inter action. We use this method to determine the spin of the electrically charge d excitations of the ground state at filling factor nu = 1.