Crystal and magnetic structures of the antiferromagnetic manganese sulfideBaLa2MnS5 by powder neutron diffraction measurements

Powder neutron diffraction measurements were performed on an antiferromagne tic manganese sulfide BaLa2MnS5 at 7 and 100 K. This sulfide has a tetragon al nuclear structure with space group I (4) over bar/mcm. The neutron diffr action data at 7 K show a collinear antiferromagnetic structure (space grou p I (4) over bar) with a propagation vector k = (1/2, 1/2, 1/2). The magnet ic moment of Mn2+ is estimated to be 4.21 mu(B) and determined to lie in a parallel direction with the c-axis. The magnetic exchange constants, (2J(1) + J(2))/k(B) and J(3)/k(B), are estimated to be -6.6 K and 0.80 K, respect ively, from the molecular field approximation.