  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. We observe that the magnitude of the spin
splitting increases with applied voltage and temperature, and is highly crystal
direction dependent, vanishing along [1 1-bar 0].
