Revealing the EuCd₂As₂ Semiconducting Band Gap via n-Type La-Doping

This is the authors' abstract. We don't add key points for this paper.

EuCd2As2 has attracted considerable interest as one of the few magnetic Weyl semimetal candidate materials, although recently, there have been emerging reports that claim it to have a semiconducting electronic structure. To resolve this debate, we established the growth of n-type EuCd2As2 crystals to directly visualize the nature of the conduction band using angle-resolved photoemission spectroscopy (ARPES). We show that La-doping leads to n-type transport signatures in both thermopower and Hall effect measurements, in crystals with n-type doping levels of 2–6 × 1017 cm–3. Both p- and n-type-doped samples exhibit antiferromagnetic ordering at 9 K. ARPES experiments at 6 K clearly show the presence of the conduction band minimum at 0.8 eV above the valence band maximum, which is further corroborated by the observation of a 0.71–0.72 eV band gap in room temperature diffuse reflectance absorbance measurements. Together, these findings unambiguously show that EuCd2As2 is indeed a semiconductor with a substantial band gap and not a topological semimetal.