Giant negative magnetoresistance in a topological hourglass candidate*

Non-symmorphic materials have been recently predicted to host protected surface fermions displaying hourglass dispersion [1]. Here we report the physical properties of Eu₅In₂Sb₆ single crystals crystallizing in the non-symmorphic space group Pbam (55) [2]. Our results show that Eu₅In₂Sb₆ is a narrow-gap antiferromagnetic insulator that exhibits giant negative magnetoresistance driven by magnetic polarons. We discuss the potential surface states in Eu₅In₂Sb₆, and the role of magnetic correlations on hourglass fermions.

[1] Z. Wang, A. Alexandradinata, R. J. Cava, and B. A. Bernevig, Nature 532, 190 (2016).
[2] Wieder et al., Science 361, 246 (2018).