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TT: Tiefe Temperaturen
TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique
TT 16.42: Poster
Samstag, 5. März 2005, 11:00–16:30, Poster TU C
Charge order in organic linear chain compounds investigated by ESR — •Belal Salameh, Michael Dumm , and Martin Dressel — 1.Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70555 Stuttgart.
We investigated the ferroelectric charge ordered state of the quasi one-dimensional organic charge-transfer salts (TMTCF)2X ( C=Se, S; X=PF6,AsF6, SbF6, BF4 and SCN) by performing comprehensive ESR experiments in the temperature range from 4 to 300 K. At high temperatures, all investigated compounds show a linear decrease of the linewidth with decreasing temperature. Below T ≈ 200 K the linewidth starts to decrease more rapidly with lowering the temperature. We will discuss different models for this general behaviour of the ESR linewidth in the organic spin chain compounds investigated. For the sulfur salts the anisotropy and the temperature dependence of the ESR linewidth change below the charge ordering (CO) transition around 100 K. The characteristic changes of the angular dependence of the linewidth well below TCO will be discussed in detail. Our findings in the charge ordered region might be due to the formation of two magnetically inequivalent TMTTF sites below the charge ordering transition temperature.