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Title: Insights from experiment and ab initio calculations into the glasslike transition in the molecular conductor κ - ( BEDT - TTF ) 2 Hg ( SCN ) 2 Cl

Abstract

We present high-resolution measurements of the relative length change as a function of temperature of the organic charge-transfer salt kappa-(BEDT-TTF) 2Hg(SCN) 2Cl. We identify anomalous features at T g ≈ 63 K which can be assigned to a kinetic glasslike ordering transition. By determining the activation energy E-A, this glasslike transition can be related to conformational degrees of freedom of the ethylene endgroups of the organic building block BEDT-TTF. As opposed to other $$\kappa$$-(BEDT-TTF) 2X salts, we identify a peculiar ethylene endgroup ordering in the present material in which only one of the two crystallographically inequivalent ethylene endgroups is subject to glasslike ordering. This experimental finding is fully consistent with our predictions from ab initio calculations from which we estimate the energy differences Delta E and the activation energies E-A between different conformations. The present results indicate that the specific interaction between the ethylene endgroups and the nearby anion layers leads to different energetics of the inequivalent ethylene endgroups, as evidenced by different ratios E A/Δ E. We infer that the ratio E A/Δ E is a suitable parameter to identify the tendency of ethylene endgroups toward glasslike freezing.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Science Foundation (NSF); German Science Foundation
OSTI Identifier:
1461306
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 7; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

Citation Formats

Gati, Elena, Winter, Stephen M., Schlueter, John A., Schubert, Harald, Müller, Jens, and Lang, Michael. Insights from experiment and ab initio calculations into the glasslike transition in the molecular conductor κ-(BEDT-TTF)2Hg(SCN)2Cl. United States: N. p., 2018. Web. doi:10.1103/PhysRevB.97.075115.
Gati, Elena, Winter, Stephen M., Schlueter, John A., Schubert, Harald, Müller, Jens, & Lang, Michael. Insights from experiment and ab initio calculations into the glasslike transition in the molecular conductor κ-(BEDT-TTF)2Hg(SCN)2Cl. United States. doi:10.1103/PhysRevB.97.075115.
Gati, Elena, Winter, Stephen M., Schlueter, John A., Schubert, Harald, Müller, Jens, and Lang, Michael. Fri . "Insights from experiment and ab initio calculations into the glasslike transition in the molecular conductor κ-(BEDT-TTF)2Hg(SCN)2Cl". United States. doi:10.1103/PhysRevB.97.075115.
@article{osti_1461306,
title = {Insights from experiment and ab initio calculations into the glasslike transition in the molecular conductor κ-(BEDT-TTF)2Hg(SCN)2Cl},
author = {Gati, Elena and Winter, Stephen M. and Schlueter, John A. and Schubert, Harald and Müller, Jens and Lang, Michael},
abstractNote = {We present high-resolution measurements of the relative length change as a function of temperature of the organic charge-transfer salt kappa-(BEDT-TTF)2Hg(SCN)2Cl. We identify anomalous features at Tg ≈ 63 K which can be assigned to a kinetic glasslike ordering transition. By determining the activation energy E-A, this glasslike transition can be related to conformational degrees of freedom of the ethylene endgroups of the organic building block BEDT-TTF. As opposed to other $\kappa$-(BEDT-TTF)2X salts, we identify a peculiar ethylene endgroup ordering in the present material in which only one of the two crystallographically inequivalent ethylene endgroups is subject to glasslike ordering. This experimental finding is fully consistent with our predictions from ab initio calculations from which we estimate the energy differences Delta E and the activation energies E-A between different conformations. The present results indicate that the specific interaction between the ethylene endgroups and the nearby anion layers leads to different energetics of the inequivalent ethylene endgroups, as evidenced by different ratios EA/Δ E. We infer that the ratio EA/Δ E is a suitable parameter to identify the tendency of ethylene endgroups toward glasslike freezing.},
doi = {10.1103/PhysRevB.97.075115},
journal = {Physical Review B},
issn = {2469-9950},
number = 7,
volume = 97,
place = {United States},
year = {2018},
month = {2}
}