  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.
