Structural and Physical Properties of the Heavy Fermion Metal Ce2NiAl6Si5

Strongly correlated electrons at the verge of quantum criticality give rise to unconventional phases of matter and behaviors, with the discovery of new quantum-critical materials driving synergistic experimental and theoretical advances. In this paper, we report the structural and physical properties of a new quaternary Ce-based heavy fermion compound, Ce2NiAl6Si5, which was synthesized via the self-flux method. This compound forms a layered tetragonal structure (space group P4/nmm) with square nets of Ce atoms separated by Si-Al or Ni-Si-Ge layers. Specific heat measurements show a low-temperature Sommerfeld coefficient of 1.4 J/mol-Ce⋅K2 with reduced entropy, indicative of significant Kondo interactions. Below 0.6 K, an increase in resistivity and a deviation in magnetic susceptibility suggest the appearance of magnetic ordering or the development of dynamic magnetic correlations, which is further supported by a bulge in the specific heat around 0.4 K. The findings of this study suggest that Ce2NiAl6Si5 is a layered heavy fermion metal naturally located near a spin-density-wave quantum critical point.