Spectral Function of Ferromagnetic $3d$ Metals: A Self-Consistent $\mathrm{LSDA}+\mathrm{DMFT}$ Approach Combined with the One-Step Model of Photoemission

The electronic structure of ferromagnetic $3d$-transition metals in the vicinity of the Fermi level is dominated by the spin-polarized $d$ bands. Experimentally, this energy region can be probed in detail by means of angle-resolved ultraviolet photoemission and inverse photoemission. In several earlier studies the measured spectra were described either within a single-particle approach based on the local spin-density approximation including matrix-element effects within the so-called one-step model or by sophisticated many-body approaches neglecting these effects. In our analysis we combine for the first time correlation with matrix-element effects to achieve an improved interpretation of photoemission data from ferromagnetic nickel.

Figure 1

Fully relativistic valence-band states of Ni(001) along $\Gamma X$. Black color indicates the LSDA-based calculation; orange (light) color denotes the states derived by the $\mathrm{LSDA}+\mathrm{DMFT}$ method obtained by suppressing the imaginary part of ${\Sigma }_{\mathrm{DMFT}}$.

Figure 2

ARUPS spectra from the Ni(001) surface Brillouin zone in the $\overline{\Gamma }\overline{X}$ direction calculated for $h\nu =21.2\mathrm{eV}$ excitation energy. Black color indicates the spin-integrated intensities; green (light) color denotes the majority-spin channel; red (dark) color indicates minority-spin emission.

Figure 3

Spin-integrated ARUPS spectra from Ni(011) along $\overline{\Gamma }\overline{Y}$ for three different angles of emission. Upper row: comparison between LSDA-based calculation and experiment [21], middle row: comparison between experiment and non-self-consistent quasiparticle calculations neglecting matrix element and surface effects [21], lower row: spin-integrated $\mathrm{LSDA}+\mathrm{DMFT}$ spectra including photoemission matrix elements (this work). Theory: solid red line, experiment: black dots.