Temperature Evolution Of Magnetic Structure Research Articles

Formations of Narrow Stripes and Vortex–Antivortex Pairs in a Quasi-Two-Dimensional Ferromagnet K2CuF4

Using cryogenic Lorentz transmission electron microscopy, we investigate the temperature evolution of magnetic structures in single crystal samples of K2CuF4 with a magnetic phase transition at 6.1...

Temperature Evolution of Magnetic Structure in Fe-Co-Si-B-Mo-P Metallic Glass by Mössbauer Spectrometry

Temperature Evolution of Magnetic Structure in Fe-Co-Si-B-Mo-P Metallic Glass by Mössbauer Spectrometry

Near room temperature spin reorientation and temperature evolution of magnetic structure in Mn substituted HoFeO3

Magnetic structure and spin reorientation transition of 45% Mn substituted HoFeO3 have been investigated using bulk magnetization, neutron powder diffraction and specific heat capacity techniques. These studies confirm the presence of antiferromagnetic ordering of Fe/Mn sublattice below 336 K. The spin reorientation (SR) transition (TSR ~ 290 K) where the magnetic structure changes from Γ4(Ax, Fy, Gz) to Γ1(Gx, Cy, Az) is confirmed by Rietveld analysis of neutron diffraction patterns taken at various temperatures. Though the spin reorientation (SR) transition is happening at 290 K, the system is found to be in mixed Γ4(Ax, Fy, Gz) + Γ1(Gx, Cy, Az) phase from room temperature to 275 K. Below 275 K, the sample exhibits a pure Γ1(Gx, Cy, Az) structure in which the weak ferromagnetic component is absent. Bulk magnetization and specific heat capacity measurements also confirm the Néel temperature and spin reorientation transitions and support the neutron diffraction analysis.

Temperature evolution of magnetic structure of HoFeO3 by single crystal neutron diffraction

We have investigated the temperature evolution of the magnetic structures of HoFeO3 by single crystal neutron diffraction. The three different magnetic structures werevfound as a function of temperature for HoFeO3. In all three phases the fundamental coupling between the Fe sub-lattices remains the same and only their orientation and the degree of canting away from the ideal axial direction varies. The magnetic polarisation of the Ho sub-lattices in these two higher temperature regions, in which the major components of the Fe moment lie along x and y, is very small. The canting of the moments from the axial directions is attributed to the antisymmetric interactions allowed by the crystal symmetry. In the low temperature phase two further structural transitions are apparent in which the spontaneous magnetisation changes sign with respect to the underlying antiferromagnetic configuration. In this temperature range the antisymmetric exchange energy varies rapidly as the the Ho sub-lattices begin to order. So long as the ordered Ho moments are small the antisymmetric exchange is due only to Fe-Fe interactions, but as the degree of Ho order increases the Fe-Ho interactions take over whilst at the lowest temperatures, when the Ho moments approach saturation the Ho-Ho interactions dominate. The reversals of the spontaneous magnetisation found in this study suggest that in HoFeO3 the sums of the Fe-Fe and Ho-Ho antisymmetric interactions have the same sign as one another, but that of the Ho-Fe terms is opposite.

Competing magnetic anisotropies in the mixed rare-earth Laves hydrides

We have studied the temperature evolution of magnetic structure in mixed Laves hydrides ${(R}^{1}{,R}^{2}){\mathrm{Mn}}_{2}{\mathrm{H}}_{4},$ where R is a rare-earth ion, by powder neutron diffraction. The spin orientation results from a compromise between the competing anisotropies of ${R}^{1},$ ${R}^{2},$ and Mn ions. The spin orientation at low temperature was analyzed using a single-ion cubic crystal-field model. We found quite an original behavior in the hydrides: the spin orientations differ from nonhydrogenated compounds, and cannot be explained by a unique set of crystal-field parameters. This suggests that the hydrogen superstructure strongly influences the anisotropy.