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TT: Fachverband Tiefe Temperaturen

TT 19: Poster Session: Correlated Electrons 1

TT 19.2: Poster

Montag, 20. März 2017, 15:00–19:00, P2-EG

An Ultrasonic Study of the Heavy-Fermion Metal YbNi₄P₂ — •Yeekin Tsui, Lars Postulka, Bernd Wolf, Ulrich Tutsch, Kristin Klimt, Cornelius Krellner, and Michael Lang — Goethe-Universität, Physikalisches Institut SFB/TR49, D-60438 Frankfurt(M), Germany

YbNi₄P₂ is a stoichiometric heavy-fermion Kondo-lattice system with a Kondo temperature TK ∼ 8 K. The material exhibits unique features among the heavy-fermion compounds including its quasi-1D crystalline and electronic structure. Furthermore, YbNi₄P₂ undergoes a second-order ferromagnetic (FM) phase transition at 0.17 K, which can be suppressed by doping with a small amount of As leading to a FM quantum-critical point (QCP). The 4f-spins remain strongly fluctuating down to the lowest measured temperatures which influence the thermodynamic and transport properties of YbNi₄P₂. Therefore, YbNi₄P₂ is the first clean system situated in the close vicinity of an FM QCP [1]. Ultrasonic measurements have proven to be a powerful probe for characterizing the intriguing properties of heavy-fermion metals. Here we present ultrasonic measurements on a single crystal of YbNi₄P₂ over a wide temperature range. Our data show clear features in the ultrasound velocity and the attenuation corresponding to crystal-electric-field effects around 30 K. Further ultrasonic measurements are being conducted at temperatures around the FM phase transition.

[1] C. Krellner et al., New Journal of Physics 13 (2011) 103014