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Tuneability and criticality in a three-dimensional stacked molecular system

Berlie, A.; Terry, I.; Szablewski, M.; Giblin, S.R.

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A. Berlie

S.R. Giblin


With the changing of physical properties through chemical substitution in mind, this work shows the applicability of this approach to organic based spin-Peierls (SP) systems. To demonstrate this we have used a well known system, potassium TCNQ, that undergoes an SP transition at TSP=396 K. Simply substituting protons for fluorine, using TCNQF4, shows a decrease in the coupling strength between TCNQ anions where the spin-Peierls transition is dramatically reduced in temperature, with KTCNQF4 showing a TSP at approximately 160 K, which is due to changes of the electron spin density across the molecule. Muon spin relaxation is a more suitable technique for determining the magnetic properties of these systems and measurements were conducted on both KTCNQ and KTCNQF4 in order to study the behavior of the SP transition. This has highlighted and shown that both transitions exhibit the same behavior and so are indeed similar; however, we have also succeeded in being able to tune the transition. Estimates of the dynamic critical exponents from both samples are obtained from the muon data and are found to be ∼0.33, corresponding to a three-dimensional (3D) antiferromagnetic system implying that spin fluctuations associated with the SP state are correlated not just along stacks of dimerized TCNQ anions. This result extends the understanding of the SP phase transition in the KTCNQ system beyond that determined from purely structural studies.


Berlie, A., Terry, I., Szablewski, M., & Giblin, S. (2016). Tuneability and criticality in a three-dimensional stacked molecular system. Physical Review B, 93(5), Article 054422.

Journal Article Type Article
Acceptance Date Dec 16, 2015
Online Publication Date Feb 24, 2016
Publication Date Feb 24, 2016
Deposit Date Mar 2, 2016
Publicly Available Date Mar 2, 2016
Journal Physical Review B
Print ISSN 2469-9950
Electronic ISSN 2469-9969
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 93
Issue 5
Article Number 054422


Accepted Journal Article (346 Kb)

Copyright Statement
Reprinted with permission from the American Physical Society: Physical Review B 93, 054422 © (2016) by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further

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