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arXiv · 2203.01790

Effect of symmetry reduction on the magnetic properties of LnIr$_2$Si$_2$ polymorphs

Kristin Kliemt·Julian Dominik Reusch·Michael Bolte·Cornelius Krellner
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Abstract

Many tetragonal compounds LnIr$_2$Si$_2$ (Ln = lanthanoid) occur in two polymorphous phases and are therefore well suited to study the relationship between crystal structure and magnetic properties. We have grown GdIr$_2$Si$_2$ single crystals of both polymorphs from a high-temperature indium flux and investigated their anisotropic magnetic properties. The higher symmetric form with the ThCr$_2$Si$_2$ structure (space group $I4/mmm$) orders antiferromagnetically at $T_{\rm N}=87\,\rm K$ while for the lower symmetric compound in the CaBe$_2$Ge$_2$ structure (space group $P4/nmm$) we determined a much lower \neel temperature $T_{\rm N}=12\,\rm K$. Our magnetic characterization of the single crystals reveals that for both compounds the magnetic moments are aligned in the $a-a$ plane of the tetragonal lattice, but that the change of the symmetry strongly effects the inplane alignment of the moment orientation. For Ln$=$Er and Ho, we confirmed the existence of LnIr$_2$Si$_2$ in the space group $P4/nmm$. The magnetic properties of these lower symmetric compounds are in remarkable difference to their related compounds in the space group $I4/mmm$.

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Kristin Kliemt, Julian Dominik Reusch, Michael Bolte, Cornelius Krellner. 2022-03-03. Effect of symmetry reduction on the magnetic properties of LnIr$_2$Si$_2$ polymorphs. https://doi.org/10.1016/j.jmmm.2022.169199

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