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TT: Fachverband Tiefe Temperaturen

TT 41: Correlated Electrons: Quantum-Critical Phenomena

TT 41.5: Vortrag

Mittwoch, 22. März 2017, 10:30–10:45, HSZ 204

Grüneisen ratio divergence at the structural quantum critical point in (Ca_0.9Sr_0.1)₃Rh₄Sn₁₃ — •Rudra Sekhar Manna¹, Andreas Wörl¹, Swee K. Goh², Kazuyoshi Yoshimura³, and Philipp Gegenwart¹ — ¹EP VI, EKM, Augsburg University, 86159 Augsburg, Germany — ²Dept. of Physics, The Chinese University of Hong Kong, Hong Kong, China — ³Dept. of Chemistry, Kyoto University, Kyoto 606-8502, Japan

Quasi-skutterudite compound Sr₃Rh₄Sn₁₃ shows a second-order structural phase transition at 138 K which can be tuned to 0 K either by applying hydrostatic pressure or by chemical pressure in (Ca_xSr_1−x)₃Rh₄Sn₁₃. At the critical concentration, x_c = 0.9, specific heat shows a pronounced enhancement (compared to the x = 0) of the low-temperature phonon (T³) contribution, possibly related to the softening of an optical mode [1]. We have performed high-resolution thermal expansion and specific heat measurements on single crystal of x = 0 and a lump of small (Ca_0.9Sr_0.1)₃Rh₄Sn₁₃ crystals. Thermal expansion also detects a strongly enhanced phonon contribution at the critical concentration. Importantly, the effective Grüneisen parameter Γ_eff = β·V_mol/κ_T·C diverges from 20 K down to below 1 K, providing evidence for quantum criticality.

[1] S. K. Goh, D. A. Tompsett, P. J. Saines, H. C. Chang, T. Matsumoto, M. Imai, K. Yoshimura, and F. M. Grosche, PRL 114, 097002 (2015).