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TT: Fachverband Tiefe Temperaturen

TT 25: Correlated Electrons: Quantum-Critical Phenomena 1

TT 25.8: Vortrag

Mittwoch, 28. März 2012, 11:30–11:45, H 3010

Ferromagnetic quantum criticality in the new heavy-fermion system YbNi₄P₂ — •Manuel Brando, Alexander Steppke, Stefan Lausberg, Robert Kuechler, Edit Lengyel, Lucia Steinke, Cornelius Krellner, Robert Borth, Michael Nicklas, Christoph Geibel, and Frank Steglich — Max-Planck-Institut für Chemische Physik fester Stoffe Nöthnitzer Str. 40, 01187 Dresden, Germany

We present measurements of the ac-susceptibility, specific heat (C) and thermal expansion (α) on single crystals of the new quasi-one-dimensional heavy-fermion system YbNi₄P₂.
YbNi₄P₂ is a Kondo-lattice system that orders ferromagnetically at a very low temperature T_c = 0.17 K [1]. Ferromagnetism can be suppressed by arsenic substitution x on phosphorus site and a ferromagnetic (FM) quantum critical point (QCP) is approached at x = 0.08.
We provide evidence that such a FM-QCP exists in YbNi₄(P_0.92As_0.08)₂ by showing that (i) the magnetic transition remains ferromagnetic between x = 0 and x = 0.08, (ii) no phase transition nor Fermi-liquid ground state down to 0.02 K can be observed at x = 0.08, and finally (iii) the Grüneisen ratio Γ = α/C strongly diverges [2] with decreasing temperature as Γ ∼ T^−0.3.
Part of this work has been supported by the DFG Research Unit 960 “Quantum Phase Transitions”.
C. Krellner et al., New J. Phys. 13 (2011) 103014
L. Zhu et al., Phys. Rev. Lett. 91 (2003) 066404