The dimensionality of quantum critical Ce₂PdAl₇Ge₄

Ce₂PdAl₇Ge₄ is a layered heavy fermion system that is “born” quantum critical [1]. It displays a diverging specific heat below 10 K without ordering down to 100 mK. Here we probe the magnetic and charge excitations to determine the dimensionality of Ce₂PdAl₇Ge₄ and the related Co analog, which orders magnetically at 1.8 K. Ce₂CoAl₇Ge₄ orders with a complex intra-unit cell magnetic order. Inelastic neutron scattering reveals on Ce₂PdAl₇Ge₄ reveals a diffuse scattering with in-plane correlations, but lacking any measurable correlations between neighboring cerium planes. Complimenting this we performed angle resolved photoemission studies in the VUV and soft X-ray regimes, and found a strongly quasi-2D electronic structure. These results indicate that Ce₂PdAl₇Ge₄ is an ideal system to study quantum criticality and non-Fermi liquid behavior in a canonical 2D Kondo lattice system.

[1] N. Ghimire et al. Phys. Rev. B 93, 205141 (2016)