Evidence of a structural quantum critical point in (CaxSr1−x)3Rh4Sn13 from a lattice dynamics study
| Autor: | Weiya Zhang, Y. Tanioku, K. T. Lai, Kodai Moriyama, Y. J. Hu, Swee K. Goh, Hibiki Kanagawa, Satoshi Tsutsui, Joichi Murakawa, Koji Kaneko, Yiu Wing Cheung, F. M. Grosche, Masayuki Imai, Kenichi Yoshimura |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Physical Review B. 98 |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.98.161103 |
| Popis: | Approaching a quantum critical point (QCP) has been an effective route to stabilize superconductivity. While the role of magnetic QCPs has been extensively discussed, similar exploration of a structural QCP is scarce due to the lack of suitable systems with a continuous structural transition that can be conveniently tuned to 0 K. Using inelastic x-ray scattering, we examine the phonon spectrum of the nonmagnetic quasiskutterudite $({\mathrm{Ca}}_{x}{\mathrm{Sr}}_{1\ensuremath{-}x}{)}_{3}{\mathrm{Rh}}_{4}{\mathrm{Sn}}_{13}$, which represents a precious system to explore the interplay between structural instabilities and superconductivity by tuning the Ca concentration $x$. We unambiguously detect the softening of phonon modes around the M point on cooling towards the structural transition. Intriguingly, at $x=0.85$, the soft mode energy squared at the M point extrapolates to zero at $(\ensuremath{-}5.7\ifmmode\pm\else\textpm\fi{}7.7)$ K, providing the first compelling microscopic evidence of a structural QCP in $({\mathrm{Ca}}_{x}{\mathrm{Sr}}_{1\ensuremath{-}x}{)}_{3}{\mathrm{Rh}}_{4}{\mathrm{Sn}}_{13}$. The enhanced phonon density of states at low energy provides the essential ingredient for realizing strong-coupling superconductivity near the structural QCP. |
| Databáze: | OpenAIRE |
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