Enhanced Mobility and Large Linear Nonsaturating Magnetoresistance in the Magnetically Ordered States of ${\mathrm{TmNiC}}_2$

We have studied the magnetic, magnetotransport, and galvanomagnetic properties of ${\mathrm{TmNiC}}_2$. We find that the antiferromagnetic and field induced metamagnetic and ferromagnetic orderings do not suppress the charge density wave. The persistence of Fermi surface pockets, open as a result of imperfect nesting accompanying the Peierls transition, results in an electronic carriers mobility of the order of $4\times {10}^3{\mathrm{cm}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ in ferromagnetic state, without any signatures for a significant deterioration of nesting properties. This is independently evidenced by high, nonsaturating linear magnetoresistance reaching 440% at $T=2\mathrm{K}$ and an analysis of the Hall conductivity. We thus demonstrate that, the coexistence of charge density wave and magnetism provides an alternative route to maintain high electronic mobility in the magnetically ordered state.

Figure 1

(a) Thermal dependence of ${\rho }_{xx}$ at zero field and ${\mu }_{0}H=9\mathrm{T}$, inset shows an expanded view of the low temperature range. (b) Magnetic field dependence of MR. Dashed line is an exemplary fit to the low field data with Eq. (5). (c) Kohler’s plot of MR, the insets depict the violation of the Kohler’s rule at moderate temperatures (upper), and in the vicinity of $T_N$ (lower).

Figure 2

(a) Thermal dependence of ${\rho }_{yx}/({\mu }_{0}H)$ measured at two different fields. Inset shows an expanded view of the low temperature range. (b) ${\rho }_{yx}({\mu }_{0}H)$ for selected temperatures. Inset shows the expanded view for the low field limit of $T=2\mathrm{K}$ curve. (c) ${\rho }_{yx}$ as a function of ${\mu }_{0}H$. Black dashed lines are typical fits with Eq. (4).

Figure 3

Thermal dependence of concentrations (a): majority carriers $n_{\mathrm{eff}}$ estimated from the high limit of ${\rho }_{yx}({\mu }_{0}H)$, right scale, minority carriers $n_H$ from fits with Eq. (4), left scale; and mobilities (b) of the minority band of, calculated by various methods: ${\mu }_{\mathrm{MR}}$ from Eq. (5), ${\mu }_{\mathrm{ext}}$ from extremum ${\sigma }_{xy}({\mu }_{0}H)$ and ${\mu }_H$ from fits with Eq. (4).