Structure and magnetic properties of the $S=3/2$ zigzag spin chain antiferromagnet BaCoTe${}_2$O${}_7$

Abstract

We report an investigation on structure and magnetic properties of the $S=3/2$ zigzag spin chain compound BaCoTe${}_2$O${}_7$. Neutron diffraction measurements reveal BaCoTe${}_2$O${}_7$ crystallizes in the noncentrosymmetric space group $Ama2$ with a canted $\uparrow \uparrow \downarrow \downarrow$ spin structure along the quasi-one-dimensional zigzag chain and a moment size of $1.89(2)\hat{I}{¼}_B$ at 2 K. Magnetic susceptibility and specific heat measurements yield an antiferromagnetic phase transition at $T_N=6.2$ K. A negative Curie-Weiss temperature $\hat{I}{˜}_{CW}=-74.7(2)$ K and an empirical frustration parameter of $f=|\hat{I}{˜}_{\text{CW}}|/T_{\text{N}}\approx 12$ is obtained from fitting the magnetic susceptibility, indicating antiferromagnetic interactions and strong magnetic frustration. By employing ultraviolet-visible absorption spectroscopy and first principles calculations, an indirect band gap of 2.68(2) eV is determined. We propose that the canted zigzag spin chain of BaCoTe${}_2$O${}_7$ may produce a change of the polarization via exchange striction mechanism.

11 pages, 5 Figures, Supplemental material