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Phonon renormalization effects accompanying the 6 K anomaly in the quantum spin liquid candidate $κ − {(BEDT-TTF)}_{2} {Cu}_{2} {(CN)}_{3}$

Masato Matsuura ^1,*, Takahiko Sasaki ², Makoto Naka³, Jens Müller⁴, Oliver Stockert⁵, Andrea Piovano⁶, Naoki Yoneyama⁷, and Michael Lang⁴

¹Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
²Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
³School of Science and Engineering, Tokyo Denki University, Saitama 350-0394, Japan
⁴Institute of Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
⁵Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany
⁶Institut Laue-Langevin (ILL), 71 avenue des martyrs, 38042 Grenoble Cedex 9, France
⁷Graduate Faculty of Interdisciplinary Research, University of Yamanashi, Kofu 400-8511, Japan

^*m_matsuura@cross.or.jp

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Phys. Rev. Research 4, L042047 – Published 20 December, 2022

DOI: https://doi.org/10.1103/PhysRevResearch.4.L042047

Abstract

The low-temperature state of the quantum spin liquid candidate $κ − {(BEDT-TTF)}_{2} {Cu}_{2} {(CN)}_{3}$ emerges via an anomaly at $T^{*} \sim 6$ K. Although signatures of this anomaly have been revealed in various quantities, its origin has remained unclear. Here we report inelastic neutron scattering measurements on single crystals of $κ − {(BEDT-TTF)}_{2} {Cu}_{2} {(CN)}_{3}$ , aiming at studying phonon renormalization effects at $T^{*}$ . A drastic change was observed in the phonon damping across $T^{*}$ for a breathing mode of BEDT-TTF dimers at $E = 4.7$ meV. The abrupt change in the phonon damping is attributed to a phase transition into a valence bond solid state based on an effective model describing the spin-charge coupling in this dimer-Mott system.

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References (41)

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Phys. Rev. Research 4, L042047– Published 20 December, 2022

Vol. 4, Iss. 4 — December - December 2022

Received 8 August 2022
Accepted 23 November 2022

DOI: https://doi.org/10.1103/PhysRevResearch.4.L042047

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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Phonon renormalization effects accompanying the 6 K anomaly in the quantum spin liquid candidate $κ − {(BEDT-TTF)}_{2} {Cu}_{2} {(CN)}_{3}$

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Phonon renormalization effects accompanying the 6 K anomaly in the quantum spin liquid candidate κ−(BEDT-TTF)2Cu2(CN)3

Abstract

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (41)

Phonon renormalization effects accompanying the 6 K anomaly in the quantum spin liquid candidate $κ − {(BEDT-TTF)}_{2} {Cu}_{2} {(CN)}_{3}$