Magnetic structure and spin reorientation of quaternary Dy2Fe2Si2C

Abstract

We have investigated the low temperature magnetic properties of Dy2Fe2Si2C by using magnetisation, specific heat, x-ray diffraction, neutron powder diffraction and 57Fe Mössbauer spectroscopy measurements over the temperature range 1.5 K–300 K. Dy2Fe2Si2C exhibits two magnetic transitions at low temperatures: an antiferromagnetic transition at ${{T}_{\text{N}}}\sim 26$ K and a spin-reorientation transition at ${{T}_{t}}\sim 6$ K. The magnetic structure above Tt can be described with a propagation vector $\mathbf{k}~=~\left(0~0~\frac{1}{2}\right)$ with the ordering of the Dy magnetic moments along the monoclinic b-axis whereas on cooling below Tt the Dy moment tips away from the b-axis towards the ac-plane. We find that the spin-reorientation in Dy2Fe2Si2C is mainly driven by the competition between the second-order crystal field term B20 and the higher-order terms, in particular B40 and B64. © 2017 IOP Publishing Ltd