Canted antiferromagnetism in the quasi-one-dimensional iron chalcogenide ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$

We report the synthesis and physical properties studies of quasi-one-dimensional (quais-1D) iron chalcogenide ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ which shares the ${\mathrm{FeSe}}_4$ tetrahedra building motif commonly seen in the iron chalcogenide superconductors. A high-quality polycrystalline sample was achieved by solid-state reaction method and characterized by x-ray diffraction, electrical resistivity, magnetic susceptibility, and neutron diffraction measurements. ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ is a narrow gap semiconductor that magnetically orders at $\sim 310$ K. Both neutron powder diffraction results and isothermal $M-H$ loops suggest a canted antiferromagnetic structure where Fe sublattices are antiferromagnetically ordered along the $c$-axis quasi-1D chain direction, resulting in a net ferromagnetic moment in the perpendicular direction along the $a$ axis with tilted angle of $18.7^{\circ }$ towards the $b$ axis.

Figure 1

(a) Schematic crystal structure of ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ and ${\mathrm{BaFe}}_2{\mathrm{Se}}_3$. (b) View from the $b$ axis for ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$. (c) Detailed microstructure of infinite chains of edge-sharing ${\mathrm{FeSe}}_4$ tetrahedra along the $c$ axis for ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$. (d) X-ray diffraction pattern and Rietveld refinement results of the ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ at room temperature.

Figure 2

Temperature dependence of resistivity on ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ and the inset shows fitting results from ln($\rho$) vs $1/T$.

Figure 3

(a) Magnetization as a function of temperature $M$($T$) of ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ measured with ZFC and FC modes at different applied magnetic fields. The top right inset shows the transition temperature determined from the $dM/Hd\mathit{T}$ vs $T$ plot. The left inset shows the Curie-Weiss fitting over the high-temperature range. (b) Magnetization as a function of field $M\left(H\right)$ of ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ measured at different temperatures from 20 to 350 K. The inset shows the fitting data after subtracting the linear antiferromagnetic contribution ${\chi }_{\mathrm{AFM}}H$ at 20 K.

Figure 4

(a) Rietveld refinement of neutron powder diffraction data of ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ at 280 K. The inset shows the increased intensity of magnetic peak when the temperature is decreased to 2 K. (b) Rietveld refinement of neutron powder diffraction data of ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$ at 2 K. The inset shows the schematics of the magnetic structure of ${\mathrm{BaFe}}_2{\mathrm{Se}}_4$.