MAGNETIC-PROPERTIES OF BARIUM HOLMIUM FLUORIDE, BARIUM ERBIUM FLUORIDE AND BARIUM THULIUM FLUORIDE - II - NEUTRON-DIFFRACTION MEASUREMENTS AND THE ORDERED ANTIFERROMAGNETIC STATE

Neutron diffraction experiments have established the nature of the ord ered antiferromagnetic state for the three compounds BaLn(2)F(8), wher e Ln = Ho, Er, and Tm. Measurements were made at temperatures from 4.2 down to 0.3 K. Parallel to the c-axis the magnetic unit cell is twice as long as the chemical unit cell. The sub-lattice magnetization has been determined, and is discussed in terms of the dipolar interactions .