The electron correlation in topological semimetals is an important subject of topological material physics. The quantum limit(QL), wherein electrons are quasi-one-dimensionally confined under the magnetic field, offers a fertile playground to study correlation induced non-trivial phases such as the topological CDW or excitonic insulator, but these phases remain to be fully explored experimentally.
In this study, we report the magnetoresistance up to 55 T for CaIrO₃, which is a strongly-correlated Dirac semimetal on the verge of Mott transition[1,2]. We observed the giant positive longitudinal magnetoresistance in the QL, which steeply increases at 9 T, shows a peak around 18 T, and decreases at higher field. The activation energy derived by the Arrhenius plot also shows non-monotonic magnetic field dependence, which agrees well with the theoretical model of CDW instability[3]. Combining with the results of non-linear current-voltage property, we propose that disordered CDW is formed in the intermediate field region (9-25 T) of QL in CaIrO₃.

[1] M. Zeb and H. Kee, PRB 86, 085149 (2012)
[2] J. Fujioka et al., Nat. Commun. 10, 362 (2019)
[3] H. Fukuyama, Solid State Commun. 26, 783 (1978)