Structure and magnetic properties of flux grown single crystals of Co3−xFexSn2S2 shandites

• Successful growth of Co3−xFexSn2S2 crystals out of self Sn flux is reported.
• The solubility is limited to x=0.53 as indicated by WDX spectroscopy.
• Unlike In-substitution, Fe results in much smaller crystal structure distortions.
• The obtained magnetic phase diagram indicates a magnetic transition at xc=0.8.
• Our results indicate that the electron count mainly affects on magnetism of Co3Sn2S2.

We report a successful single crystal growth of the shandite-type half-metallic ferromagnet Co3Sn2S2, and its Fe-substituted compounds, Co3−xFexSn2S2, by employing the flux method. Although Fe3Sn2S2 is unstable phase, we found that using the self Sn flux enables us to obtain single phase crystals up to x=0.53. The chemical composition of the grown plate-shaped single crystals was examined using wavelength-dispersive X-ray spectroscopy. The shandite structure with R  3̅m symmetry was confirmed by powder X-ray diffraction and the crystal structure parameters were refined using the Rietveld method. Magnetization measurements show suppression of the ferromagnetic order upon Fe-substitution , as well as in other substituted systems such as In- and Ni-substituted Co3Sn2S2. The almost identical magnetic phase diagrams of the Fe- and In-substituted compounds indicate that the electron number is dominantly significant to the magnetism in the Co-based shandite.

Magnetic phase diagrams of Co3−xFexSn2S2 and Co3Sn2−yInyS2 and general crystal structure of T3M2S2 (T=Co, Fe and M=Sn, In) Shandites. Inset on left shows the x and y dependences of c/a ratio, respectively, while inset on right shows an image of a single crystal of Co3−xFexSn2S2 grown out of Sn flux on a mm scale.Figure optionsDownload as PowerPoint slide