<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>EuCd</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mrow><mml:msub><mml:mrow><mml:mi>As</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math>: A Magnetic Semiconductor
David Santos‐Cottin, Ivan Mohelský, J. Wyzula, F. Le Mardelé, I. Kapon, S. Nasrallah, N. Barišić, Irina Živković, Jian-Rui Soh, Fei Guo, K. Rigaux, M. Puppin, J. Hugo Dil, B. Gudac, Zoran Rukelj, Mario Novak, Alexey B. Kuzmenko, C. C. Homes, T. Dietl, M. Orlita, Ana Akrap
Abstract
${\mathrm{EuCd}}_{2}{\mathrm{As}}_{2}$ is now widely accepted as a topological semimetal in which a Weyl phase is induced by an external magnetic field. We challenge this view through firm experimental evidence using a combination of electronic transport, optical spectroscopy, and excited-state photoemission spectroscopy. We show that the ${\mathrm{EuCd}}_{2}{\mathrm{As}}_{2}$ is in fact a semiconductor with a gap of 0.77 eV. We show that the externally applied magnetic field has a profound impact on the electronic band structure of this system. This is manifested by a huge decrease of the observed band gap, as large as 125 meV at 2 T, and, consequently, by a giant redshift of the interband absorption edge. However, the semiconductor nature of the material remains preserved. ${\mathrm{EuCd}}_{2}{\mathrm{As}}_{2}$ is therefore a magnetic semiconductor rather than a Dirac or Weyl semimetal, as suggested by ab initio computations carried out within the local spin-density approximation.