SKM 2023 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Correlated Electrons: Other Materials
TT 10.7: Talk
Monday, March 27, 2023, 16:45–17:00, HSZ 204
Mott criticality in the deuterated variant of κ-(BEDT-TTF)2 Cu[N(CN)2]Br studied by thermal expansion under He-gas pressure — •Yassine Agarmani, Harald Schubert, Bernd Wolf, and Michael Lang — PI, GU Frankfurt, CRC/TRR288, DE
The understanding of the nature of the critical behavior at the Mott transition has recently been given a new twist by thermodynamic measurements on the Mott insulator κ-(ET)2Cu[N(CN)2]Cl (κ-Cl)]. While so far mainly electronic scenarios have been considered to describe the Mott transition, the observations of strong non-linearities in the strain-stress relation around the Mott critical endpoint in κ-Cl showed that the lattice degrees of freedomn play a crucial role [1]. This behavior has been found to be consistent with the proposed scenario of critical elasticity [2], which considers a non-perturbatively strong coupling of the elastic- to the electronic degrees of freedom, causing a softening of the lattice. These observations raise the question of the implication of critical elasticity for our understanding of the general phase diagram of the κ-(ET)2X family. To address this question, we have chosen a system related to κ-Cl, namely the fully deuterated κ-(ET)2Cu[N(CN)2]Br, which is known to be near the Mott critical endpoint at ambient pressure. By using an extension [3] of the setup used in [1], which enables us to fine-tune the He-gas pressure while performing high-resolution measurements of length changes, we aim to compare our results with those on κ-Cl in terms of the extension of the range of critical elasticity.
[1] Gati et al., Sci. Adv. 2, e1601646 (2016)
[2] Zacharias et al., PRL 109, 176401 (2012)
[3] Agarmani et al., RSI 93, 113902 (2022)