%0 Journal Article
%A Dutta, Rajesh
%A Thoma, Henrik
%A Sazonov, Andrew
%A Náfrádi, Bálint
%A Meven, Martin
%A Gukasov, Arsen
%A Kocsis, Vilmos
%A Zeitler, Uli
%A Puri, Alessandro
%A Tokunaga, Yusuke
%A Taguchi, Yasujiro
%A Tokura, Yoshinori
%A Bordács, Sándor
%A Kézsmárki, István
%A Hutanu, Vladimir
%T Magnetic structure of the two-dimensional XY antiferromagnet Sr$_2$CoSi$_2$O$_7$ studied using single-crystal neutron diffraction
%J Physical review / B
%V 107
%N 1
%@ 2469-9950
%C Woodbury, NY
%I Inst.
%M FZJ-2023-04487
%P 014420
%D 2023
%X We report a combined polarized and unpolarized neutron diffraction study on a multiferroic Sr$_2$CoSi$_2$O$_7$ (SCSO) single crystal below and above the antiferromagnetic ordering temperature $T_N$ = 6.5 K. Unpolarized neutron diffraction measurements at 15 K confirm the melilite-type tetragonal $P\overline{4}2_1m$ space group as the parent structure of SCSO. The low temperature study at 2.3 K, in contrast, reveals symmetry lowering with the orthorhombic Cmm′2′ and $P2_12′_12′$ magnetic space groups being equally possible. In these $Cmm′2′$ and $P2_12′_12′$ magnetic space groups we obtain a very similar ordered magnetic moment about 2.86 and 2.94μB/Co$^{2+}$, respectively, which lies in the $ab$ plane. Our spin polarized flipping ratio measurements under an applied magnetic field of 6 T in the paramagnetic state support the results of our bulk magnetization data, indicating strong easy-plane spin anisotropy, responsible for the in-plane order below $T_N$.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000927608900003
%R 10.1103/PhysRevB.107.014420
%U https://juser.fz-juelich.de/record/1018017