Antiferromagnetic resonance in the BEDTTTF series

Abstract
The antiferromagnetic ground state of beta -(BEDTTTF)2ICl2 and AuCl2 is probed by antiferromagnetic resonance. The parameters deduced (position of the magnetic axes and magnitude of the anisotropy) are discussed using a strongly localised picture of the spin ordering as suggested by the strongly dimerised structure of the ICl2 salt and the low electrical conductivity of these compounds. An excellent agreement is found between experimental and calculated results, assuming the dipole-dipole interactions are at the origin of the observed anisotropy.