Exciton exchange splitting in wide GaAs quantum wells

We determine the exciton exchange splitting in a wide GaAs quantum well. Ou r method is based on applying a magnetic field parallel to the layers and m easuring the oscillator strength ratio of the Zeeman split lines in two lin ear polarizations. We develop a theoretical model to describe the effect of the magnetic field on the exciton spectrum, and use it to determine the ex change splitting in a 22-nm quantum well to be 22 +/- 3 mu eV. These measur ements also allow us to make an accurate determination of the value of q = 0.03, the Luttinger parameter which appears in the cubic term of the valenc e band Zeeman Hamiltonian. [S0163-1829(99)51348-9].