Landau point on a nematic-isotropic transition line

Abstract
Measurements of the magnetic-field-induced birefringence are reported for the micellar system potassium laurate-1-decanol-D2O in the vicinity of a Landau point on a nematic-isotropic transition line. The cubic coefficient of the Landau expansion for the isotropic phase changes sign with composition. In presence of the field the nematic-isotropic transition smooths out on one side of the Landau point, while on the other side a sharp transition from a uniaxial to a biaxial state persists.