Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 25: Focus Session: Atomic-Scale Characterization of Correlated Ground States in Epitaxial 2D Materials
O 25.2: Topical Talk
Dienstag, 6. September 2022, 11:00–11:30, H2
Magnetic order in a coherent Kondo lattice in the 1T/1H TaSe2 heterostructure — Wen Wan1, Rishav Harsh1, Paul Dreher1, Sandra Sajan1, Antonella Meninno2, Ion Errea2, Fernando de Juan1, and •Miguel Ugeda1 — 1Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain — 2Centro de Física de Materiales (CSIC-UPV-EHU), Paseo Manuel de Lardizábal 5, 20018 San Sebastián, Spain
Kondo lattice systems are of fundamental importance for our understanding of quantum criticality and unconventional superconductivity. At the heart of their complexity lies the competition between the opposing forces of Kondo screening and magnetic interactions, which is revealed at very low temperatures as the moments start behaving coherently and eventually determines the fate of the ground state. While our understanding of Kondo lattices has traditionally relied on technically challenging strongly correlated bulk f-electron systems, new light is being shed on the problem thanks to heterostructures of 2D transition metal dichalcogenides, which realize a tunable Kondo lattice platform in a simple material. Here, we study the 1T/1H-TaSe2 heterostructure with high-resolution Scanning Tunneling Spectroscopy at 300 mK, and show a well resolved splitting of the Kondo peak, which increases monotonically in a non-linear fashion in the presence of an out-of-plane magnetic field. This behavior is unexpected for a fully screened Kondo lattice, and it originates instead from a ground state with residual magnetic order, consistent with a Kondo coupling much below the critical point in the Doniach phase diagram.