We report the canted antiferromagnetic (AFM) structure together with a spin reorientation in a single chain quasi-one-dimensional (Q-1D) iron chalcogenide ${\mathrm{Ba}}_2{\mathrm{FeSe}}_3$. ${\mathrm{Ba}}_2{\mathrm{FeSe}}_3$ crystallizes in Pnma (No. 62) orthorhombic structure with linear single iron chains consisting of corner-shared distorted ${\mathrm{FeSe}}_4$ tetrahedra along the $b$ axis. ${\mathrm{Ba}}_2{\mathrm{FeSe}}_3$ is a narrow-gap semiconductor and orders AFM below 60 K. Modeling of neutron powder diffraction data reveals a canted AFM ground state of magnetic space group $Pa21/c$ (BNS No. 14.80) with commensurate propagation vector $\mathbf{k}=(0, \frac{1}{2}, 0)$, where the Fe ion spins are AFM aligned with up-down-up-down $(\uparrow \text{−}\downarrow \text{−}\uparrow \text{−}\downarrow )$ sequence along the Q-1D chain direction of the $b$ axis. In the magnetically ordered state, the canting of magnetic moments reorients from the $ac$ plane to the $ab$ plane below 30 K, with a 10° tilting angle toward the $a$ axis, and the magnetic moment does not induce a net moment in either orientation. The density functional theory results indicate that an $\uparrow \text{−}\downarrow \text{−}\uparrow \text{−}\downarrow$ AFM state is stabilized along the chain direction. In this work, we elucidate the unique canted AFM of the iron chalcogenide and pave the way for searching exotic physics in Q-1D ${\mathrm{Ba}}_2{\mathrm{FeSe}}_3$.

Close

PrevNext

View figure in article

• Antiferromagnetism
• Exchange interaction
• Magnetic order
• Magnetic phase transitions
• Magnetic susceptibility
• Spin texture
• DFT+U
• Neutron diffraction