Lattice effects and entropy change at the Mott transition of a quasi-2D organic conductor

✍ Scribed by Michael Lang; Mariano de Souza; Andreas Brühl; Christian Strack; Bernd Wolf; Dieter Schweitzer

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 205 KB
• Volume: 403
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2007.10.154

✦ Synopsis

Layered organic charge-transfer salts of the kÀðBEDTÀTTFÞ 2 X family have emerged as exemplary systems for exploring effects of strong electron-electron correlations. Here we report on high-resolution dilatometric investigations on a fully deuterated crystal of the X ¼ Cu½NðCNÞ 2 Br salt, where the Mott metal-insulator (MI) transition-a key phenomenon of strongly correlated electron systemscan be explored through temperature sweeps. Measurements of the uniaxial expansivities reveal discontinuous lattice changes at T MI ' 14 K, accompanied by a striking in-plane anisotropy. The entropy change at T MI , determined from the volume change, is small, indicating that T MI coincides with the Ne´el-temperature T N at this point in the phase diagram.