Magnetic Properties of Cr1-xMnx As System

Studies on X-ray crystallographic, magnetic, neutron diffraction and transport properties have been made of the system Cr 1- x Mn x As (0≤ x ≤0.9). All the members of the system undergo a transition from MnP structure to NiAs structure. Magnetic measurements have revealed the existence of three distinct magnetic regions and the magnetic structures of these regions have been found from neutron diffraction measurements. On the basis of these experimental data, magnetic and crystallographic phase diagrams have been constructed. In particular, CrAs exhibits a discontinuous change in the lattice constants at the Néel temperature which was obtained to be 265°K. The electrical resistivity and thermoelectric power show a strong anomaly at the temperature where the magnetic order disappears. The observed helical spin arrangement may be stabilized by the distorion of the Fermi surface which is caused by the formation of a new zone boundary.