Abstract

Powder neutron diffraction measurements were performed on an antiferromagnetic manganese sulfide BaLa₂MnS₅ at 7 and 100 K. This sulfide has a tetragonal nuclear structure with space group I/mcm. The neutron diffraction data at 7 K show a collinear antiferromagnetic structure (space group I) with a propagation vector k = (1/2, 1/2, 1/2). The magnetic moment of Mn²⁺ is estimated to be 4.21 μ_B and determined to lie in a parallel direction with the c-axis. The magnetic exchange constants, (2J₁ + J₂)/k_B andJ₃/k_B, are estimated to be −6.6 K and 0.80 K, respectively, from the molecular field approximation.