2006/10/31 by M. de Souza, M De Souza, A. Brühl +6 · 3 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Organic and Molecular Conductors Research #Physics of Superconductivity and Magnetism #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.99.037003
published as Physical Review Letters 99, 037003 (2007) · 4 pages, 4 figures
openalex publication_date 2007/07/18 · arxiv created 2007/12/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
Discontinuous changes of the lattice parameters at the Mott metal-insulator transition are detected by high-resolution dilatometry on deuterated crystals of the layered organic conductor \ensuremathκ\mathrm\text\ensuremath-(BEDT\mathrm\text\ensuremath-TTF)2Cu[N(CN)2]Br. The uniaxial expansivities uncover a striking and unexpected anisotropy, notably a zero effect along the in-plane c axis along which the electronic interactions are relatively strong. A huge thermal expansion anomaly is observed near the end point of the first-order transition line enabling us to explore the critical behavior with very high sensitivity. The analysis yields critical fluctuations with an exponent \stackrel\texttildelow\ensuremathα\ensuremath≃0.8\ifmmode±\else\textpm\fi0.15 at odds with the novel criticality recently proposed for these materials [Kagawa et al., Nature (London) 436, 534 (2005)]. Our data suggest an intricate role of the lattice degrees of freedom in the Mott transition for the present materials.