We performed scanning tunneling microscopy (STM) and spectroscopy on a (001) surface of the ferromagnetic semimetal ${\mathrm{EuB}}_6$. Large-amplitude oscillations emanating from the elastic scattering of electrons by the surface impurities are observed in topography and in differential conductance maps. Fourier transform of the conductance maps embracing these regions indicate a holelike dispersion centered around the $\overline{\mathrm{\Gamma }}$ point of the two-dimensional Brillouin zone. Using density functional theory slab calculations, we identify a spin-split surface state, which stems from the dangling $p_z$ orbitals of the apical boron atom. Hybridization with bulk electronic states leads to a resonance enhancement in certain regions around the $\overline{\mathrm{\Gamma }}$ point, contributing to the remarkably strong real-space response around static point defects, which are observed in STM measurements.

• Received 18 November 2019
• Revised 11 May 2020
• Accepted 13 May 2020

DOI:https://doi.org/10.1103/PhysRevB.101.235421

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Published by the American Physical Society