Magnetic structure of quasi-1D antiferromagnetic TaFe1+yTe3 with two-leg zigzag ladders

We report the magnetic structure of TaFe1+yTe3 single crystals by means of neutron diffraction measurements. TaFe1+yTe3 possesses a layered structure with a formation of two-leg zigzag ladders along the b-axis. We find that TaFe1+yTe3 undergoes an antiferromagnetic transition at 178 K with Fe1 spins of the intra-ladders ferromagnetically aligned while spins of the inter-ladders antiferromagneitcally coupled. Furthermore, spins of the neighboring interstitial Fe2 (y) ions order parallel to the Fe1 spins of each ladder. These findings are distinct from the magnetic structure of the recently-discovered spin-ladder compound BaFe2Se3. TaFe1+yTe3 may serve as an interesting quasi-one dimensional ferromagnetic system.