EPR LINESHAPE OF MN IN BCCD SINGLE-CRYSTALS IN THE INCOMMENSURATE PHASE

For the interpretation of the EPR lineshape of incommensurate phases t here exist many theoretical models. We suppose a simple physical model to interpret the lineshape of the Mn2+ EPR spectrum of the first inco mmensurate phase of betaine calcium chloride dihydrate (BCCD) and disc uss it in comparison with other models. Furthermore, we investigate th e critical behavior of BCCD at the normal to incommensurate phase tran sition on the basis of our model. The influence of the Mn2+ impurities on the phase sequence of BCCD is investigated by dielectric measureme nts.