INVESTIGATIONS BY MAGNETIC MEASUREMENTS AND NEUTRON-DIFFRACTION STUDIES OF THE MAGNETIC-ORDERING OF MN8O10CL3

The three dimensional manganese oxychloride Mn8O10Cl3 belongs to the q uadratic symmetry, space group I4/mmm with cell parameters: a = 9.275( 2) Angstrom and c = 13.057(2) Angstrom, (Z = 4) and orders magneticall y below 29 K. The susceptibility versus temperature curve suggests a n onclassical ferrimagnetic behavior. Above 200 K, manganese oxychloride follows a classical Curie-Weiss law. Spontaneous magnetization increa ses from 5 K, reaching a maximum at 20 K and decreases to zero at 30 K . A neutron diffraction study has been performed between 2 and 100 K. The magnetic structure is built on two magnetic sublattices. One is fe rrimagnetic collinear with the a axis, and the second one is frustrate d. Magnetization behavior can be explained in terms of orientation and intensity changes in magnetic moments carried by manganese atoms.