Magnetic ordering RAgSB2 compounds

The magnetic structures of the polycrystalline samples of RAgSb2 (R = Ce, P r, Nd, Tb-Tm) are determined. All compounds crystallize in the tetragonal Z rCuSi2-type of crystal structure and except CeAgSb2 they are antiferromagne ts with a Neel temperature of 11 K for R = Tb and 2 K for Tm. CeAgSb2 below T-C = 9.5 K is ferromagnet with the magnetic moment equal to 0.33 mu(B) an d parallel to c-axis. In NdAgSb2 the sine modulated magnetic ordering descr ibed by the wave vector k = (0.5435,0,0) is observed. Below T-N a collinear antiferromagnetic structure with the magnetic (a, a, 2c) for R = Pr and (2 a, a, c) for R = Tb, Dy, Ho, and Er is observed. For He-compound with an in crease in temperature the coexistence of two structures is observed: commen surate collinear and incommensurate sine modulated. In TmAgSb2 the coexiste nce of the two phases is observed at T = 1.4 K. With an increase in tempera ture only the incommensurate phase stays.