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TT: Fachverband Tiefe Temperaturen

TT 11: Heavy Fermions

TT 11.8: Vortrag

Montag, 18. März 2024, 17:00–17:15, H 3005

Realization of heavy fermion phase diagram in van der Waals heterostructures — •Somesh Chandra Ganguli — Aalto University School of Science, Finland

The heavy fermion compounds host a rich playground for correlated quantum states. In these compounds, the itinerant electrons in s, p or d shells interact with the lattice of localized magnetic moments in f shell via Kondo effect giving rise to Kondo lattice, resulting in a large effective mass as well as a gap in the conduction electron spectra, known as heavy fermion hybridization gap, which upon chemical doping can host unconventional superconductivity and quantum criticality. Recently, we have been able to demonstrate that heavy fermionic behavior can be created artificially using vdW epitaxy, using heterostructure of 2 different phases of the same material TaS₂. Stacking 1H-TaS₂ hosting 2-D conduction electrons, and 1T-TaS₂ hosting localized magnetic moments gives rise to Kondo lattice and heavy-fermion hybridization gap. We also observe, that in vdW heterostructure of similar material NbSe₂, the Kondo coupling (JK) does not overcome the exchange coupling (JAF) between the localised magnetic moments. Furthermore, the chemical potential becomes site dependent, driving the 1T-NbSe₂/1H-NbSe₂ system into the doped Mott insulator regime with exotic charge order. These observations establish artificial vdW heterostructures as a versatile platform to navigate the heavy fermion phase diagram.

Keywords: Heavy fermion; Kondo lattice; Mott insulator