Internal magnetic field in thin ZnSe epilayers

Strain-induced spin splitting is observed and characterized using pump-probe Kerr rotation spectroscopy in n-ZnSe epilayers grown on GaAs substrates. The spin splitting energies are mapped out as a function of pump-probe separation, applied voltage, and temperature in a series of samples of varying epilayer thicknesses and compressive strain arising from epilayer-substrate lattice mismatch. The strain is independently quantified using photoluminescence and X-ray diffraction measurements. The authors observe that the magnitude of the spin splitting increases with applied voltage and temperature and is highly crystal direction dependent, vanishing along [11¯0].