Giant magnetoresistance inCe2Fe17

Using a single-phase sample of ${\mathrm{Ce}}_2{\mathrm{Fe}}_{17}$ with the rhombohedral ${\mathrm{Th}}_2{\mathrm{Zn}}_{17}$-type structure, we measured the magnetization, resistivity, and specific heat under various magnetic fields up to 5.5 T. Below $T_c=125\mathrm{}$ K, giant magnetoresistance (GMR) is induced by the metamagnetic transition from the antiferromagnetic to ferromagnetic states. The value of $\Delta \rho /\rho \left(\cong {\rho }_{\mathrm{AF}}-{\rho }_{\mathrm{F}}\right)/{\rho }_{\mathrm{AF}})$ reaches 0.85 at 4.2 K, while the value γ $(\cong C/T$ at 0 K) of 351 ${\mathrm{m}\mathrm{J}/\mathrm{K}}^2/\mathrm{mole}$ in zero field only decreases ∼20% by the metamagnetic transition. These results suggest that GMR is due to the closing of a superzone gap formed by antiferromagnetic ordering of Fe spins, while the large γ value is due to valence fluctuations of the $\mathrm{C}\mathrm{e}-4f$ electrons, weakly dependent on magnetic field.