J. Phys. IV France
Volume 114, April 2004
Page(s) 411 - 417

J. Phys. IV France
114 (2004) 411
DOI: 10.1051/jp4:2004114099

Electronic states of a strongly correlated two-dimensional system, Pd(dmit) 2 salts, controlled by uni-axial strain and counter cations

R. Kato1, 1, A. Tajima1, N. Tajima1, A. Nakao1 and M. Tamura1

1  RIKEN, JST-CREST, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan

The uni-axial strain effects in a series of anion radical salts, ${\rm g}\beta $'-Me 4Z [ Pd(dmit) 2] 2, ${\rm g}\beta $ '-Et 2Me 2Z[ Pd(dmit) 2] 2 (Z=P, As, Sb) and Et 2Me 2N[ Pd(dmit) 2] 2 are described. They are classified into a strongly correlated two-dimensional system. The conduction layer consists of strongly dimerized Pd(dmit) 2 units forming a distorted triangular lattice. The electronic structure can be well described by the dimer model. The half-filled conduction band originates from the HOMO of the Pd(dmit) 2 molecule. At ambient pressure, these salts are Mott-insulators where the frustration plays a crucial role. The electronic state of this system would be governed by the on-site Coulomb energy, the band width, and the degree of frustration, each of which is sensitive to the intra- and inter-dimer interactions. The application of uni-axial pressure induces a variety of physical properties including superconductivity. The choice of the counter cation affects the electronic state under the uni-axial strain. Key words. Pd(dmit) 2 - Uni-axial strain - Resistivity.

© EDP Sciences 2004