Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 5: f-Electron Systems and Heavy Fermions I
TT 5.7: Vortrag
Montag, 12. März 2018, 11:00–11:15, H 3005
A Study of the Ferromagnetic and Lifshitz Phase Transitions in the Heavy-Fermion Metal YbNi4P2 by Ultrasonic Measurements — •Yeekin Tsui, Lars Postulka, Bernd Wolf, Ulrich Tutsch, Kristin Kliemt, Cornelius Krellner, and Michael Lang — Goethe-Univeristät, Physikalisches Institut SFB/TR49, D-60438 Frankfurt(M),Germany
YbNi4P2 is a stoichiometric heavy-fermion Kondo-lattice system with a Kondo temperature of 8 K [1]. This system is situated in the close vicinity of a ferromagnetic (FM) quantum-critical point (QCP) and can be tuned to the FM QCP by substituting a small amount of phosphorous by arsenic [1]. Recently, nine field-induced Lifshitz transitions (LTs) have been proposed in YbNi4P2 [2] from the results of the transport and thermodynamic measurements, revealing a complicated electronic band structure of the system. We have performed ultrasonic measurements on single crystals of YbNi4P2 to deepen the understanding of these phase transitions. We found clear features in the ultrasound velocity (v) and the attenuation (α) corresponding to crystal-electric-field and Kondo effects. However, we detected no or very small anomalies in v or α at the expected FM phase transition in the longitudinal c33 mode, reflecting a weak coupling of the corresponding symmetry strain to the magnetic structure. On the other hand, pronounced features were identified at the proposed Lifshitz transitions at roughly 0.4, 6 and 7 T clearly demonstrating the different character of these transitions.
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