Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 71: Correlated Electrons: Poster Session

TT 71.19: Poster

Mittwoch, 18. März 2015, 15:00–18:00, Poster B

Single crystal growth of the heavy fermion compounds YbRh₂Si₂ and YbNi₄P₂ — •Constantin Butzke, Kristin Kliemt, and Cornelius Krellner — Physikalisches Institut, Goethe Universität Frankfurt, 60438 Frankfurt am Main, Germany

Heavy fermion systems are model systems to unravel the exciting physics around quantum-phase transitions. Studying these emergent phenomena necessitates the preparation of large and high-quality single crystals. We report on the optimization of the single crystal growth for two Yb-based quantum critical materials, YbRh₂Si₂ and YbNi₄P₂. The prototype heavy-fermion system YbRh₂Si₂ is situated extremely close to an unconventional antiferromagnetic (AF) quantum critical point (QCP). The AF ordering (T_N = 70 mK) can be further lowered by chemically induced negative pressure using Ir-substitution. The QCP is reached for an Ir-substitution of x≈ 0.1 in Yb(Rh_1−xIr_x)₂Si₂ [1]. Here, we report on the optimization of the crystal growth of the substitution series as well as of the unsubstituted compound. We also report on our attempts to determine the melting point of YbRh₂Si₂ and present a phase analysis of the molten compound. In the heavy fermion metal, YbNi₄P₂, a ferromagnetic (FM) transition at T_C = 0.17   K was observed recently and a FM QCP is reached at x ≈ 0.1 in YbNi₄(P_1−xAs_x)₂. We report on the crystal growth of YbNi₄P₂ by Czochralski method out of a Ni-P flux from a levitated melt. The obtained crystals were characterized by Laue X-ray scattering, X-ray powder diffraction, EDX microprobe analysis and resistivity measurements.

[1] S. Friedemann et al., Nature Phys. 5, 465 (2009).