Dielectric ordering and colossal magnetodielectricity in the antiferromagnetic insulating state of l-ÑBEDT-TSFÖ2FeCl4

E. Negishi,1 T. Kuwabara,1 S. Komiyama,2 M. Watanabe,2 Y. Noda,2 T. Mori,3 H. Matsui,1 and N. Toyota1 1Physics Department, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan 2Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan 3Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan sReceived 27 October 2004; published 28 January 2005d