J. Phys. IV France
Volume 114, April 2004
Page(s) 67 - 71

J. Phys. IV France
114 (2004) 67
DOI: 10.1051/jp4:2004114012

Field induced spin density wave phases in (TMTSF) 2ClO 4 at high magnetic field

S. Haddad1, S. Charfi-Kaddour1, C. Nickel2, M. Héritier2 and R. Bennaceur1

1  Laboratoire de Physique de la Matière Condensée, Faculté des Sciences de Tunis, 1060 Tunis, Tunisia
2  Laboratoire de Physique des Solides, Bât. 510, Université Paris Sud, 91405 Orsay Cedex, France

We propose a model to study the spin density wave (SDW) phases under a high magnetic field in the relaxed (TMTSF) 2ClO 4 salt where the ClO -4 anions undergoe an orientational ordering transition. This opens a gap at the original Fermi surface and leads to a two band energy spectrum. We show that, in the high field regime, a competition takes place between the interband and the intraband SDW order parameters. We find that the intraband SDW component has always the highest critical temperature but it is due to two coexisting order parameters. This coexistence tends to destabilize the corresponding phase as the temperature decreases. Eventually, a first order transition takes place from the original SDW phase to a new phase originating from interband processes. The obtained results agree with the experimental phase diagram. Key words. Organic conductors - Spin-density wave - Quantum Hall effect

© EDP Sciences 2004