Relation between Structural and Magnetic Properties of Compound MnAs1-xPx(0≦x≦0.275)

The crystallographic parameters of compounds MnAs 1- x P x (0≦ x ≦0.275) are determined as a function of temperature between about 100 and 600 K. It is found that these crystals except for MnAs take a MnP type structure in low temperature side and transform to a NiAs type at critical temperatures. These structural transitions are of second kind and accompanied with very large dilation (∼10%) of crystal volume. In order to see the relationship between the structural and magnetic properties, the temperature variation of magnetic susceptibilities of the compounds is also measured. Simple analysis of the experimental results, based on the Curie-Weiss law, reveals the way in which the spin value of Mn atoms and the exchange interaction between them depend on the crystal voluem (or lattice parameter).