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Title: Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3

Abstract

The quasi-two-dimensional organic charge-transfer salt κ-(BEDT-TTF)2Cu2(CN)3 is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despite intensive investigations of the material’s low-temperature properties, several important questions remain to be answered. Particularly puzzling are the 6 K anomaly and the enigmatic effects observed in magnetic fields. Here we report on low-temperature measurements of lattice effects which were shown to be particularly strongly pronounced in this material. A special focus of our study lies on sample-to-sample variations of these effects and their implications on the interpretation of experimental data. By investigating overall nine single crystals from two different batches, we can state that there are considerable differences in the size of the second-order phase transition anomaly around 6 K, varying within a factor of 3. In addition, we find field-induced anomalies giving rise to pronounced features in the sample length for two out of these nine crystals for temperatures T< 9 K. We tentatively assign the latter effects to B-induced magnetic clusters suspected to nucleate around crystal imperfections. These B-induced effects are absent for the crystals where the 6 K anomaly ismore » most strongly pronounced. The large lattice effects observed at 6 K are consistent with proposed pairing instabilities of fermionic excitations breaking the lattice symmetry. The strong sample-to-sample variation in the size of the phase transition anomaly suggests that the conversion of the fermions to bosons at the instability is only partial and to some extent influenced by not yet identified sample-specific parameters.« less

Authors:
 [1];  [2];  [2];  [3];  [4];  [2]
  1. IIT Tirupati, Tirupati (India); Goethe Univ. Frankfurt (M), Frankfurt (M) (Germany)
  2. Goethe Univ. Frankfurt (M), Frankfurt (M) (Germany)
  3. National Science Foundation, Arlington, VA (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Goethe Univ. Frankfurt (M), Frankfurt (M) (Germany); Univ. Estadual Paulista, Sao Paulo (Brazil)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
German Research Foundation (DFG); USDOE
OSTI Identifier:
1488414
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Crystals
Additional Journal Information:
Journal Volume: 8; Journal Issue: 2; Journal ID: ISSN 2073-4352
Publisher:
MDPI
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; organic compounds; quantum spin frustration; quantum spin liquids; thermal expansion

Citation Formats

Manna, Rudra Sekhar, Hartmann, Steffi, Gati, Elena, Schlueter, John, de Souza, Mariano, and Lang, Michael. Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3. United States: N. p., 2018. Web. doi:10.3390/cryst8020087.
Manna, Rudra Sekhar, Hartmann, Steffi, Gati, Elena, Schlueter, John, de Souza, Mariano, & Lang, Michael. Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3. United States. https://doi.org/10.3390/cryst8020087
Manna, Rudra Sekhar, Hartmann, Steffi, Gati, Elena, Schlueter, John, de Souza, Mariano, and Lang, Michael. Tue . "Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3". United States. https://doi.org/10.3390/cryst8020087. https://www.osti.gov/servlets/purl/1488414.
@article{osti_1488414,
title = {Low-Temperature Lattice Effects in the Spin-Liquid Candidate κ-(BEDT-TTF)2Cu2(CN)3},
author = {Manna, Rudra Sekhar and Hartmann, Steffi and Gati, Elena and Schlueter, John and de Souza, Mariano and Lang, Michael},
abstractNote = {The quasi-two-dimensional organic charge-transfer salt κ-(BEDT-TTF)2Cu2(CN)3 is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despite intensive investigations of the material’s low-temperature properties, several important questions remain to be answered. Particularly puzzling are the 6 K anomaly and the enigmatic effects observed in magnetic fields. Here we report on low-temperature measurements of lattice effects which were shown to be particularly strongly pronounced in this material. A special focus of our study lies on sample-to-sample variations of these effects and their implications on the interpretation of experimental data. By investigating overall nine single crystals from two different batches, we can state that there are considerable differences in the size of the second-order phase transition anomaly around 6 K, varying within a factor of 3. In addition, we find field-induced anomalies giving rise to pronounced features in the sample length for two out of these nine crystals for temperatures T< 9 K. We tentatively assign the latter effects to B-induced magnetic clusters suspected to nucleate around crystal imperfections. These B-induced effects are absent for the crystals where the 6 K anomaly is most strongly pronounced. The large lattice effects observed at 6 K are consistent with proposed pairing instabilities of fermionic excitations breaking the lattice symmetry. The strong sample-to-sample variation in the size of the phase transition anomaly suggests that the conversion of the fermions to bosons at the instability is only partial and to some extent influenced by not yet identified sample-specific parameters.},
doi = {10.3390/cryst8020087},
journal = {Crystals},
number = 2,
volume = 8,
place = {United States},
year = {Tue Feb 06 00:00:00 EST 2018},
month = {Tue Feb 06 00:00:00 EST 2018}
}

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Figures / Tables:

Figure 1 Figure 1: Overview of the coefficients of thermal expansion for $κ$-(BEDT-TTF)2Cu2(CN)3 single crystal MP 1049#2 (symbols) measured along the in-plane $b$- and $c$-axis for $T$ ≤ 200 K. The solid gray line corresponds to data for single crystals from batch KAF 5078 reported previously by Manna et al..

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Works referencing / citing this record:

Thermal Expansion Studies on the Spin‐Liquid‐Candidate System κ‐(BEDT‐TTF) 2 Ag 2 (CN) 3
journal, February 2019

  • Hartmann, Steffi; Gati, Elena; Yoshida, Yukihiro
  • physica status solidi (b), Vol. 256, Issue 9
  • DOI: 10.1002/pssb.201800640

Electrodynamics in Organic Dimer Insulators Close to Mott Critical Point
journal, April 2018

  • Pinterić, Marko; Rivas Góngora, David; Rapljenović, Željko
  • Crystals, Vol. 8, Issue 5
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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.