Tuning Low Temperature Physical Properties of CeNiGe₃ by Magnetic Field

We have studied the thermal, magnetic, and electrical properties of the ternary intermetallic system CeNiGe$_{3}$ by means of specific heat, magnetization, and resistivity measurements. The specific heat data, together with the anisotropic magnetic susceptibility, was analyzed on the basis of the point charge model of crystalline electric field. The $J$\,=\,5/2 multiplet of the Ce$^{3+}$ is split by the crystalline electric field (CEF) into three Kramers doublets, where the second and third doublet are separated from the first (ground state) doublet by $\Delta_{1}$ $\sim$ 100\,K and $\Delta_{2}$ $\sim$ 170\,K, respectively. In zero field CeNiGe$_{3}$ exhibits an antiferromangeic order below $T_{N}$ = 5.0\,K. For \textbf{H}\,$\parallel$\,\textbf{a} two metamagnetic transitions are clearly evidenced between 2\,$\sim$\,4\,K from the magnetization isotherm and extended down to 0.4\,K from the magnetoresistance measurements. For \textbf{H}\,$\parallel$\,\textbf{a}, $T_{N}$ shifts to lower temperature as magnetic field increases, and ultimately disappears at $H_{c}$ $\sim$ 32.5\,kOe. For $H\,>\,H_{c}$, the electrical resistivity shows the quadratic temperature dependence ($\Delta\rho = A T^{2}$). For $H \gg H_{c}$, an unconventional $T^{n}$-dependence of $\Delta\rho$ with $n > 2$ emerges, the exponent $n$ becomes larger as magnetic field increases. Although the antiferromagnetic phase transition temperature in CeNiGe$_{3}$ can be continuously suppressed to zero, it provides an example of field tuning that does not match current simple models of Quantum criticality.