Electronic properties of (DMTSA)BF4 at ambient pressure

Organic conductor (DMTSA)BF₄ [DMTSA: 2,3dimethyl-tetra-sleno-antracene] is a compound composed of an electron donor DMTSA and a monovalent acceptor BF$_4^-$. In the salt, the electronic system is expected to be the Mott-Hubbard insulator. However, its conductivity at room temperature is 200~400$\Omega^-1$cm^-1 and behaves metallic above ∼2OOK. At ambient pressure, we found anomalies both in the DC conductivity components and in the permittivity at ~80K, similar to those in (TMTTF)₂X associated with charge ordering at ~100K. In the insulating state under low pressure, we found that the sample shows non-linear conduction with threshold. We discuss the possible origin of the anomalies and the apparent similarity with the non-linear electric conduction by the density wave sliding.