Resonant photoemission of Ga_1-xMn_xAs at the Mn L edge

Ga_1-xMn_xAs, x = 0.043, has been grown ex situ on GaAs(100) by low-temperature molecular-beam epitaxy. On the reprepared p(1 x 1) surface, resonant photoemission of the valence band shows a 20-fold enhancement of the Mn 3d contribution at the L₃ edge. The difference spectrum is similar to our previously obtained resonant photoemission at the Mn M edge, in particular a strong satellite appears and no clear Fermi edge ruling out strong Mn 3d weight at the valence-band maximum. The x-ray absorption lineshape differs from previous publications. Our calculation based on a configuration-interaction cluster model reproduces the x-ray absorption and the L₃ on-resonance photoemission spectrum for model parameters Δ, U_dd, and (pdσ) consistent with our previous work and shows the same spectral shape on and off resonance thus rendering resonant photoemission measured at the L₃ edge representative of the Mn 3d contribution. At the same time, the results are more bulk sensitive due to a probing depth about twice as large as for photoemission at the Mn M edge. The confirmation of our previous results obtained at the M edge calls recent photoemission results into question which report the absence of the satellite and good agreement with local-density theory.