Study of quasi-one dimensional magnet Ti₄MnBi₂ by neutron scattering

We report the investigation of magnetic structure of Ti₄MnBi₂ that crystallizes into a tetragonal structure (space group: I 4/mcm, No. 140). The distance between two Mn-ions along the chain is relatively small (~2.5 A) while the distance between two adjacent chains is relatively large (~7.5 A), indicating the probable quasi-one dimensional magnetic character of the materials. T

We carried out powder diffraction experiments down to T = 0.05 K. The results shows that there is no change of the diffraction pattern between 0.05 K and 6 K, indicating the ordered moment at 0.05 K, if any, is below 0.3 μ_B (the sensitivity of neutron powder diffraction), much smaller than the expected full moment (1 μ_B). From the single crystal neutron diffraction experiment at T = 2.5 K, We observed two weak forbidden nuclear reflections from, based on which we carried out the representation analysis and obtained a candidate for the magnetic structure, which is composed of antiferromagnetic spins along the spin chain (c axis) and ferromagnetic spins in between the chain (ab plane).