Orientation-dependent magneto-Clapeyron equation

Effects of an applied magnetic field on the phase transition temperature of anisotropic diamagnetic materials including crystals and liquid crystals were studied on the basis of a simple extension of the Clapeyron equation, The transition temperature was expressed as a function of the orientation of the material with respect to the applied field. Calculations for the inching points of the trans azobenzene crystal and a superdrawn polyethylene fiber showed that the shift of the melting point due to the orientation was of the order of 10(-5)-10(-4) K. Larger shifts (similar to 10(-3) K) were expected in the case of anisotropic-isotropic transitions in liquid crystal systems where their transition enthalpy is smaller by one to two orders than that for solid-liquid transitions.