Miguel M Ugeda

Kondo lattices are ideal testbeds for the exploration of heavy-fermion quantum phases of matter. While our understanding of Kondo lattices has traditionally relied on complex bulk f-electron systems, transition metal dichalcogenide (TMD) heterobilayers have recently emerged as simple, accessible and tunable 2D Kondo lattice platforms where, however, their ground state remains to be established. In this talk, I will discuss the emergence of magnetic order in the 1T/1H-TaSe2 heterobilayer [1]. Our scanning tunneling microscopy/spectroscopy measurements at 340 mK demonstrate spin coherence in a 2D Kondo lattice as opposed to the well-studied isolated-moment Kondo physics. Unexpectedly, we show that our observations are only compatible with long-range antiferromagnetic order driven by indirect RKKY interactions and, more importantly, does not condense into a Kondo insulator state as commonly assumed for this type of heterostructures. The observation of coherence behavior demonstrates that long sought Kondo phenomenology can be observed in such accessible systems, drawing a pathway towards the exploration of quantum criticality, Kondo breakdown transitions, non-Fermi liquid behavior and unconventional superconductivity in the strict two-dimensional limit.

Reference: Wen Wan, et al., arxiv:2207.00096v2 (2022)