Bera, A.K.; Lake, B.; Stein, W.-D.; Zander, S.: Magnetic correlations of the quasi-one-dimensional half-integer spin-chain antiferromagnets SrM2V2O8 (M = Co, Mn). Physical Review B 89 (2014), p. 094402/1-13

Magnetic correlations of two isostructural quasi-one-dimensional (1D) antiferromagnetic spin-chain compounds SrM2V2O8 (M = Co, Mn) have been investigated by magnetization and powder neutron diffraction. Two different collinear antiferromagnetic (AFM) structures, characterized by the propagation vectors, k = (0 0 1) and k = (0 0 0), have been found below ~ 5.2 and ~42.2 K for the Co and Mn compounds, respectively. For the Mn compound, AFM chains (along the c axis) order ferromagnetically within the ab plane, whereas, for the Co compound, AFM chains order ferromagnetically/antiferromagnetically along the a/b direction. The critical exponent study confirms that the Co andMn compounds belong to the Ising and Heisenberg universality classes, respectively. For both compounds, short-range spin-spin correlations are present over a wide temperature range above TN. The reduced ordered moments at base temperature (1.5 K) indicate the presence of quantum fluctuations in both compounds due to the quasi-1D magnetic interactions.