Carrier-density dependence of magnetotransport in correlated Dirac semimetal CaIrO${}_3$

We report the carrier density dependence of the magnetotransport property in the correlated Dirac semimetal CaIrO${}_3$. In the dilute carrier density region ($n_{\mathrm{H}}$ $\sim 2.2\times {10}^{16}$${\mathrm{c}\mathrm{m}}^{-3}$) at $2\mathrm{K}$, the mobility exceeds $1.0\times {10}^5$${\mathrm{c}\mathrm{m}}^2\mathrm{/}\mathrm{V}\mathrm{s}$ at $2\mathrm{K}$, and the transverse magnetoresistance (MR) reaches $2,000$% at $12\mathrm{T}$. The analysis of quantum oscillations and Hall conductivity shows that the Fermi velocity is nearly independent of the cross-sectional area of the Fermi surface, or equivalently the carrier density, supporting a $k$-linear dispersion of the Dirac node. The field dependence of magnetoresistivity is nearly $B$-linear in the moderate carrier density region ($n_{\mathrm{H}}\ge 4\times {10}^{16}$cm${}^{-3}$), but scales with $B^{\alpha }$ ($\alpha >2$) in the lower carrier density region. The variation of magnetoresistivity is likely affected by the enhanced long-range Coulomb interaction in the quantum limit, where Dirac electrons are subject to the magnetic confinement.