SKM 2023 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: f-Electron Systems and Heavy Fermions II

TT 9.1: Talk

Monday, March 27, 2023, 15:00–15:15, HSZ 201

Quantum oscillations in heavy-fermion ferromagnet YbNi₄P₂ over many Zeeman induced Lifshitz transitions — •William Broad¹, Sven Friedemann¹, Owen Moulding¹, Takaki Muramatsu¹, Kristin Kliemt², and Cornelius Krellner² — ¹University of Bristol, Bristol, United Kingdom — ²Goethe-Universität, Frankfurt am Main, Germany

YbNi₄P₂ is a heavy-fermion metal situated near a very rare ferromagnetic quantum critical point (FM QCP). Understanding the nature of this ferromagnetism requires knowledge of the Fermi surface; it has been speculated that this FM QCP is enabled by a quasi-1D Fermi surface. At the same time, the strongly renormalised band structure is readily modified by relatively small magnetic fields, with nine Lifshitz transitions below 20 T due to Zeeman splitting. Here, we present Shubnikov–de Haas oscillations up to 35T, including detailed rotation and mass studies. We present analysis over several of these Lifshitz transitions, observing frequency changes and appearances/disappearances. We model the band structure with DFT calculations of the local 4f reference compound LuNi₄P₂ and use rigid-band shifts to approximate the effect of the Kondo hybridisation. At highest fields, the Fermi surface is well modelled with a small shift to increase the Fermi volume. As the field is reduced, we find better agreement with a larger shift corresponding to stronger hybridisation of 4f electrons. Finally, we present models for the topology of the Lifshitz transitions.