Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 28: Correlated Electrons: Quantum-Critical Phenomena - Experiment
TT 28.11: Vortrag
Dienstag, 8. März 2016, 12:45–13:00, H21
Enhancement of effective Grüneisen parameter near structural quantum critical point in (Ca0.9Sr0.1)3Rh4Sn13 — •Rudra Sekhar Manna1, 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
The interplay between superconductivity and structural instabilities in quasi-skutterudite compounds is playing an important role in recent years. 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 (CaxSr1−x)3Rh4Sn13. A structural quantum phase transition occurs at a critical concentration xc = 0.9. The specific heat for xc = 0.9, measured in a magnetic field to suppress superconductivity indicates a pronounced enhancement of the phonon (T3) contribution at low-temperature compared to the x = 0 sample, possibly related to the softening of an optical phonon mode [1, 2]. We have performed high-resolution thermal expansion and specific heat measurements on a lump of small (Ca0.9Sr0.1)3Rh4Sn13 crystals. Thermal expansion shows a huge enhancement of phonon contribution compared to x = 0 sample. Moreover, the effective Grüneisen parameter Γeff = β·Vmol/κT·C displays a significant enhancement upon cooling, indicative of quantum criticality.
[1] S. K. Goh et al., PRL 114, 097002 (2015).
[2] W. C. Yu et al., PRL 115, 207003 (2015).