학술논문
Revealing the EuCd_{2}As_{2} Semiconducting Band Gap via n-type La-Doping
Document Type
Working Paper
Author
Nelson, Ryan A.; King, Jesaiah; Cheng, Shuyu; Williams, Archibald J.; Jozwiak, Christopher; Bostwick, Aaron; Rotenberg, Eli; Sasmal, Souvik; Kao, I-Hsuan; Tiwari, Aalok; Jones, Natalie R.; Cai, Chuting; Martin, Emma; Dolocan, Andrei; Shi, Li; Kawakami, Roland; Heremans, Joseph P.; Katoch, Jyoti; Goldberger, Joshua E.
Source
Subject
Language
Abstract
EuCd_{2}As_{2} 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 EuCd_{2}As_{2} crystals, to directly visualize the nature of the conduction band using angle resolve photoemission spectroscopy (ARPES). We show that La-doping leads to n-type transport signatures in both the thermopower and Hall effect measurements, in crystals with doping levels at 2 - 6 x 10^{17} e^{-} cm^{-3}. Both p-type 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 EuCd_{2}As_{2} is indeed a semiconductor with a substantial band gap and not a topological semimetal.