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The electron correlation in topological semimetals has been an important subject in topological material physics. The quantum confinement of strongly correlated relativistic electrons into quasi-one-dimension under a strong magnetic field (B) offers a fertile ground for exploring the emergent correlated topological phenomena, but has been rarely realized so far.

In this study, we report a largely anisotropic quantum-limit magnetoresistance (MR) in perovskite CaIrO₃, which is a strongly-correlated Dirac semimetal on the verge of Mott transition [1,2]. The resistivity for B || a shows an insulating behavior with the MR ratio exceeding 2000 % around 18 T, whereas the B || c MR always remains metallic. This is accounted for in terms of that the large difference of Fermi velocity of the n = 0 Landau level between B || a and B || c due to the B-direction dependent 5d orbital electron hopping, which triggers the different instability toward the charge density wave formation for the one-dimensional (|| B) dispersive n = 0 Landau level [3].

 

[1] M. Zeb and H. Kee, Physical Review B 86, 085149 (2012)

[2] J. Fujioka et al., Nature Communications 10, 362 (2019)

[3] R. Yamada et al., npj Quantum Materials 7, 13 (2022)