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We have determined the magnetic structures of the Er and Fe sublattices in ErFe 6 Sn 6 by high-resolution neutron powder diffraction and Mössbauer spectroscopy on the 166 Er, 57 Fe and 119 Sn isotopes. The crystal space group is orthorhombic Cmcm. The Fe sublattice is antiferromagnetic with a Néel temperature of 560(5) K and it orders along the [100] direction with a magnetic space group C P m c m and a propagation vector [010]. The Fe magnetic moment at 1.5 K is 2.4 ± 0.6 µ B . The Er sublattice orders independently of the Fe sublattice at 4.8 ± 0.4 K and comprises a ferromagnetic mode along [100] and an antiferromagnetic mode along [010], with a propagation vector [0 1 2 0] i.e. cell-doubling along [010]. The magnetic space group of the Er sublattice within the magnetic unit cell is Pbc m , a subgroup of Cmcm. At 1.5 K the ferromagnetic and antiferromagnetic components of the Er 3+ magnetic moment (determined by a combination of neutron diffraction and magnetization measurements) are 5.9 ± 0.1 and 4.9 ± 1.5 µ B , respectively, yielding a net Er moment of 7.7 ± 1.5 µ B . The Er 3+ magnetic moment derived from 166 Er Mössbauer spectroscopy is 8.5(1) µ B .

We have used time-of-flight (TOF) neutron powder diffraction, and both Fe57 and Sn119 Mössbauer spectroscopy over the temperature range 2–600 K to determine the magnetic ordering mode of the Fe sublattice in YFe6Sn6. The crystal structure is orthorhombic (space group Immm). The Fe sublattice orders antiferromagnetically with a Néel temperature of 558(5) K. The TOF neutron diffraction patterns obtained at 4 and 293 K show that the antiferromagnetic ordering of the Fe sublattice is along [100] with a propagation vector q=[010]. The magnetic space group is IPm′m′m′. This magnetic structure is confirmed by our Sn119 Mössbauer spectra.

We have used Time-of-Flight (ToF) neutron powder diffraction, and both 57 Fe and 119 Sn Mössbauer spectroscopy, to study the independent magnetic ordering behavior of the Fe and Ho sublattices in HoFe 6 Sn 6 . The crystal structure of HoFe 6 Sn 6 is orthorhombic (space group Immm). The Fe sublattice orders antiferromagnetically with a Néel temperature of 559(5) K, determined by differential scanning calorimetry. The ToF neutron diffraction patterns obtained at 30 K and 295 K show that the antiferromagnetic ordering of the Fe sublattice is along [100] with a propagation vector q = [010]. The magnetic space group of the Fe sublattice is and the Fe magnetic moment at 30 K is 2.31(5). This magnetic structure is confirmed by our 119 Sn Mössbauer spectra in which 37% of the Sn nuclei experience a substantial transferred hyperfine field from the Fe sublattice while the remaining 63% of the Sn sites show no magnetic splitting, due to the cancellation of transferred hyperfine fields from the Fe neighbors, in full agreement with our Wigner-Seitz cell calculations for each of the eight Sn sites in the HoFe 6 Sn 6 structure. The Ho sublattice orders ferromagnetically at 9(1) K. ToF data obtained at 4 K show that the Ho moments are aligned along [001] i.e., perpendicular to the Fe ordering. The magnetic space group of the Ho sublattice is . The refined Ho magnetic moments at 4 K are 4.4(2) and 5.2(2) at the 2a and 4h sites, respectively.

Modifications in the structural and magnetic properties of co-precipitated cobalt ferrite nanoparticles can be accomplished by varying the annealing time periods during the synthetic process. Experimental results show that high-purity cobalt ferrite nanoparticles are obtained using a co-precipitation process. The dependence of the crystallite sizes on the annealing time was successfully demonstrated using XRD and SEM. Finally, vibrating sample magnetometer analyses show that the magnetic properties of the cobalt ferrite nanoparticles depend on their relative particle sizes.