Spin-reorientation in quaternary Dy_2Fe_2Si_2C

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Australian Institute of Nuclear Science and Engineering
The low temperature magnetic properties of Dy_2Fe_2Si_2C have been investigated by magnetisation, specific heat, neutron powder diffraction and "5"7Fe Mössbauer spectroscopy measurements. In contrast to other R_2Fe_2Si_2C compounds, we found that Dy_2Fe_2Si_2C undergoes two successive magnetic transitions at low temperatures. The first magnetic transition at T_N = 26(2) K is associated with the transition from paramagnetic to antiferromagnetic states, whereas our neutron diffraction and "5"7Fe Mössbauer spectroscopy studies reveal that the second magnetic transition at T_t = 6(2) K is likely related to a spin-reorientation of the Dy moments rather than the independent ordering of the Fe sublattice. The magnetic structure above T_t can be described with a propagation vector k = [0 0 1/2] with the ordering of the Dy magnetic moments along the monoclinic b-axis, whereas on cooling below T_t the Dy moment tips away from the b-axis towards the ac-plane. Magnetocrystalline anisotropy energy calculations show that a canted magnetic structure is more energetically favourable below T_t than b-axis order due to the important influence of higher-order crystal field terms at low temperatures, thus explaining the unique occurrence of spin reorientation in Dy_2Fe_2Si_2C compared with other R_2Fe_2Si_2C compounds.
Anisotropy, Antiferromagnetism, Crystal field, Crystal lattices, Electron temperature, Magnetic properties, Moessbauer effect, Neutron diffraction, Paramagnetism, Spin orientation, Temperature dependence
Susilo, R. A., Cadogan, J. M., Hutchison, W. D., Stewart, G. A., Campbell, S. J., & Avdeev, M. (2016). Spin-reorientation in quaternary Dy_2Fe_2Si_2C. Paper presented at 13th AINSE-ANBUG Neutron Scattering Symposium (AANSS 2016); Sydney, NSW, Australia, 29-30 November 2016.