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

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.