Local order and hybridization effects for Mn ions probed by resonant soft x-ray spectroscopies: The Mn:CdTe(110) interface revisited

The electronic structure and the local ordering of Mn:CdTe(110) interface, produced by evaporating at room temperature (RT) 2 ML of Mn on a CdTe(110) single-crystal surface, have been probed by soft x-ray spectroscopies. Strong Mn-Te hybridization effects are found both in core level and valence-band photoemission spectra. The analysis of resonant photoelectron-diffraction patterns indicates that, already at RT, Mn atoms diffuse into CdTe down to the fourth layer, replacing the isovalent Cd atoms in the lattice.

Figure 1

(Color online) Comparison of $\text{Mn}2p$ XPS spectra from (a) Mn:CdTe(110), (b) ${\text{Zn}}_{1-x}{\text{Mn}}_x\text{Te}$ (adapted from Ref. 28), (c) MnO (adapted from Ref. 29), and from (d) a reference metallic Mn thick film deposited on a silicon wafer. (e) Calculated $\text{Mn}2p$ XPS spectrum for ${\text{Mn}}^{2+}$ ion with charge-transfer derived configurations ($\Delta =2.1\text{eV}$, $T=2.2\text{eV}$, $Q=6.0\text{eV}$, and $U=5.1\text{eV}$).

Figure 2

(Color online) (a) Two dimensional plot of RESPES data collected from the valence-band region for different photon energies ranging from 636 to 655 eV; (b) XAS profile measured at the $\text{Mn}L$ threshold; (e) Mn RSW obtained by subtracting from the spectrum collected at resonance (c) the spectrum collected off resonance (d). CI cluster calculations of the VB spectrum (g) obtained by adding a proper background (dotted line) to the calculated $\text{Mn}3d$ spectral weight (f). Weight of the $|3d^4⟩$ (h) and $|d^{5}L⟩$ (j) configurations in the calculated spectrum.

Figure 3

(Color online) Calculated anisotropies $\chi$ for the substitutional Mn atom in different layers. (a) First layer, (b) sum of first and second layers, (c) sum of first to third layers, (d) sum of first to fourth layers, and (e) calculated interstitial Mn atoms (sum of first to fourth layers), (f) measured anisotropy from the $\text{Te}4d$ shallow-core levels (photoelectron kinetic $\text{energy}=594.5\text{eV}$), (g) measured anisotropy from the $\text{Cd}4d$ shallow-core levels (photoelectron kinetic $\text{energy}=627\text{eV}$), (h) measured anisotropy obtained by considering the signal integrated over the resonantly enhanced valence-electron emission.