SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 51: Correlated Electrons: Charge Order
TT 51.7: Vortrag
Donnerstag, 30. März 2023, 16:45–17:00, HSZ 103
Lifshitz transition at the onset of superconductivity from mismatched nesting in TiSe2 — •Roemer Hinlopen1, Owen Moulding1,2, Felix Flicker3, Charles Sayers4, Enrico Da Como4, Jasper van Wezel5, and Sven Friedemann1 — 1University of Bristol, UK — 2Institut Néel, Grenoble, France — 3Cardiff University, UK — 4University of Bath, UK — 5University of Amsterdam, The Netherlands
Fermi surface reconstructions and topological (Lifshitz) transitions can have a profound effect on the electronic ground state of a metal. For example, re-entrant superconductivity (SC) in URhGe may be due to the appearance of a small pocket [1], whereas in Bechgaard salts [2] and doped BaFe2As2 [3] the appearance of large pockets from mismatched nesting may give rise to SC within the magnetic phase.
Here, we report quantum oscillation measurements and DFT calculations under pressure in the prototypical charge density wave (CDW) compound TiSe2. We observe the emergence of new Fermi surface pockets at 2 GPa within the CDW arising as a result of mismatched nesting. This Lifshitz transition coincides with the emergence of superconductivity [4], suggesting an intimate link between SC and the presence of these Fermi pockets similar to BaFe2As2. This suggests that SC in TiSe2 might be of extended s±-wave character - the first such case in a CDW system.
[1] Yelland, Nat. Phys. 7, 890 (2011)
[2] Bourbonnais, C. R. Physique 12, 532 (2011)
[3] Liu, Nat. Phys. 6, 419 (2010)
[4] Kusmartseva, PRL 103, 236401 (2009)