Angle-resolved photoemission study ofGa1−xMnxAs

Abstract

Ga 1Ϫx Mn x As, xϭ0.043, has been grown ex situ on GaAs͑100͒ by low-temperature molecular-beam epitaxy. On the reprepared p(1ϫ1) surface, resonant photoemission of the valence band shows a 20-fold enhancement of the Mn 3d contribution at the L 3 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 L 3 on-resonance photoemission spectrum for model parameters ⌬, U dd , and (pd) consistent with our previous work and shows the same spectral shape on and off resonance thus rendering resonant photoemission measured at the L 3 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.

Different origins of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

“…In this case a hole mediated Zener model for the ferromagnetism is appropriate. After having fixed the Coulomb and exchange constants U and J to values that reproduce accurately both the position of the Mn d shell coming from photoemission data [37] and the spin-splitting of the GaAs valence band coming from the LDA-SIC method [20], we have estimated the Zener mean-field exchange parameter N β to be ∼ −2.8 eV. We believe this is the correct value that should be used in model Hamiltonian calculations.…”

“…Our fitting criterion was to choose U and J in order to obtain the best energy position of the Mn d band compared with that of available photoemission data [37]. This fit fixes U and J respectively to 4.5 eV and 1.0 eV.…”

Surface treatments and magnetic properties of Ga1−xMnxAs thin films

“…Many experiments were performed in the past years, such as X-ray photoemission (XPS) [9], resonant photoemission (RPES) [10], angular resolved ultraviolet photoemission (ARUPS) [11]. The sample surfaces are routinely prepared by mean of repeated cycles of Ar + ion sputtering and thermal annealing, keeping the temperature lower than 250°C.…”

Atom-by-atom substitution of Mn in GaAs and visualization of their hole-mediated interactions

“…2b. These resonance states have been anticipated 19 to play a role in interpretation of photoemission 20 and infrared optical conductivity 21,22 measurements of Ga 1-x Mn x As.…”