Exploring the Charge-Ordering Transition in TMTTF$ 2$X via Thermal Expansion Measurements - Condensed Matter > Strongly Correlated ElectronsReportar como inadecuado




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Abstract: We report results of high-resolution measurements of the \emph{c$^*$}-axisexpansivity $\alpha {c^{*}}$ at the charge-ordering CO transition for thequasi-1D TMTTF$ {2}$X compounds with X = SbF$ 6$ and Br and make a comparisonwith previous results for the X = PF$ 6$ and AsF$ 6$ salts. For X = SbF$ 6$,due to the screening of the long-range Coulomb forces, a sharp $\lambda$-typeanomaly is observed at $T {CO}$, which contrasts with the step-like mean-fieldanomaly at $T {CO}$ for PF$ 6$ and AsF$ 6$, where CO occurs in the Mott-Hubbardcharge-localized regime. For the latter two salts, a negative contribution to$\alpha {c^{*}}$ is observed above $T {CO}$. This feature is assigned to theanions- rigid-unit modes, which become inactive for $T$ $<$ $T {CO}$. Our$\alpha {c^{*}}$ results for the X = Br salt, where such rigid-unit modes areabsent, reveal no traces of such negative contribution, confirming the modelbased on the anions- rigid-unit modes for the X = PF$ 6$ and AsF$ 6$ salts.



Autor: Mariano de Souza, Daniel Hofmann, Pascale Foury-Leylekian, Alec Moradpour, Jean-Paul Pouget, Michael Lang

Fuente: https://arxiv.org/







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