Evolution of Magnetism in Ce$_4$Ge$_7$ under Magnetic Field and Pressure
We report the magnetic and transport properties of single-crystalline Ce$_4$Ge$_7$, which crystallizes in a non-centrosymmetric orthorhombic structure (space group C222$_1$). It undergoes an antiferromagnetic transition at $T_N$ = 7.3 K. When a magnetic field is applied along the $b$-axis, a metamagnetic transition occurs at 1.3 T (at 2 K). Correspondingly, this transition gives rise to an anomalous Hall effect, which is dominated by the intrinsic Karplus-Luttinger mechanism. Under hydrostatic pressure, $T_N$ of Ce$_4$Ge$_7$ initially increases slightly and is then gradually suppressed. For pressures above $P_c$ = 10.2 GPa, no magnetic order is observed. The divergence of the $A$ coefficient, the maximum of the residual resistivity, and the non-Fermi liquid behavior around $P_c$ indicate the possible existence of an antiferromagnetic quantum critical point in Ce$_4$Ge$_7$.