Electronic band structure of the Co pnictide A(CoX)₂ (A=Ca, Eu and X=As, P) probed by ARPES

The pnictide family of transition metals is being widely studied for emergence of new collective quantum states. In the iron-family, the suppression of the antiferromagnet order is accompanied with the emergence of superconductivity [1] and the Ni-based family has been demonstrated to show an electronic liquid nematic ground state [2]. The Co-pnictide family (ACo₂X₂, A=Ba,Ca,Eu,... X=As,P) has been discussed in the framework of itinerant magnetism of conducting electrons and non-Fermi liquid scenarios. Besides, some of these Co-pnictides have been predicted to be topological Weyl semimetals where the low-energy excitations are Weyl fermions [3]. The experimental observation of these surface states gives an unequivocal proof that a particular compound is a Weyl semimetal [4]. Here, by means of ARPES and DFT, we report the experimental and theoretical band structure of the magnetic Co-pnictide ACo₂X₂ (A = Ca, Eu and X = As, P). We address the role of the dimensionality, disorder and the possible observation of topological physics.

[1] David C. Johnston. Advances in Physics, 2010.

[2] Y. Yao et al., Nature Comm. 13, 4535 (2022)

[3] Yuanfeng, Xu et al., Nature, 586, 702-707 (2020).

[4] Su-Yang Xu et al., Science, 349, 613-617 (2015).