Two magnetic orderings and a spin-flop transition in spin-1 systemSrNi2(PO4)2

Abstract

Magnetic properties of ${\text{SrNi}}_{2}{({\text{PO}}_{4})}_{2}$ are investigated by means of susceptibility, magnetization, heat-capacity, and $^{31}\text{P}$ NMR measurements. Our experimental results show that ${\text{SrNi}}_{2}{({\text{PO}}_{4})}_{2}$ is a three-dimensional antiferromagnet with two magnetic orderings at $\ensuremath{\sim}23$ and $\ensuremath{\sim}10\text{ }\text{K}$. It is suggested that canted antiferromagnetic ordering at $\ensuremath{\sim}23\text{ }\text{K}$ may correspond to a N\'eel noncollinear spin arrangements of ${\text{Ni}}^{2+}$ ions, and such noncollinear spin arrangements further induce spin rotations into a steady collinear antiferromagnetic phase below $\ensuremath{\sim}10\text{ }\text{K}$ with decreasing temperature. Also, spin-flop transition is observed at a critical field below $\ensuremath{\sim}10\text{ }\text{K}$, showing magnetic anisotropy in the system.