Magnetic correlations of the quasi-one-dimensional half-integer spin-chain antiferromagnets SrM2V2O8(M = Co, Mn)

Abstract

Magnetic correlations of two isostructural quasi-one-dimensional (1D) antiferromagnetic spin-chain compounds Sr${M}_{2}$V${}_{2}$O${}_{8}$ (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 $\ensuremath{\sim}$5.2 and $\ensuremath{\sim}$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 and Mn 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 ${T}_{N}$. 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.