Synthesis and structural characterization of $2\text{Dioxane}\cdot 2{\text{H}}_2\text{O}\cdot {\text{CuCl}}_2$: Metal-organic compound with Heisenberg antiferromagnetic $S=\frac{1}{2}$ chains

A metal-organic compound $2\text{Dioxane}\cdot 2{\text{H}}_2\text{O}\cdot {\text{CuCl}}_2$ has been synthesized and structurally characterized by x-ray crystallography. Magnetic susceptibility and zero-field inelastic neutron scattering have also been used to study its magnetic properties. It turns out that this material is a weakly coupled one-dimensional $S=\frac{1}{2}$ Heisenberg antiferromagnetic chain system with chain direction along the crystallographic $c$ axis and the nearest-neighbor intrachain exchange constant $J=0.85\left(4\right)\text{meV}$. The next-nearest-neighbor interchain exchange constant $J^{\prime }$ is also estimated to be 0.05 meV. The observed magnetic excitation spectrum from inelastic neutron scattering is in excellent agreement with numerical calculations based on the Müller ansatz.

Figure 1

(Color online) Crystal structure of CuDCl (a) view along the $\mathbf{c}$ axis showing the well-separated bilayers structure. (b) View along the $\mathbf{b}$ axis showing how ${\text{Cu}}^{2+}$ ions are linked into a 1D chain. The chain axis is along the $\mathbf{c}$ direction. Dashed lines show the superexchange Cu-Cl-H-O-Cu pathway. The gray outline is one unit cell. Color coding is as follows: pink: Cu, green: Cl, blue: C, red: H, and yellow: O.

Figure 2

Magnetic susceptibility as a function of temperature in a single-crystal sample of CuDCl. Inset: enlarged low-temperature part of magnetic susceptibility, the solid line is a fit to the model as described in the text.

Figure 3

(Color online) (a) False-color contour map of measured inelastic neutron-scattering intensity in CuDCl as a function of transferred energy $\hslash \omega$ and transferred wave vector along the $\left(1,0,l\right)$direction at $T=1.6\text{K}$, where the background is subtracted as described in the text. (b) Instrument resolution-convolved-model calculation of two-spinon continuum Müller approximation with $J=0.85\text{meV}$. Solid lines are the predicted lower and upper bounds of the spinon continuum with $J=0.85\text{meV}$.

Figure 4

Typical scans of background-subtracted neutron-scattering intensity vs transferred energy $\hslash \omega$ in CuDCl at $T=1.9\text{K}$ (a) zone center $\left(h,0,-l\right)$ and (b) zone boundary $\left(h,0,-0.5\right)$. Solid lines are the fits to the data based on Müller approximation of two-spinon continuum convolved with the instrument resolution.

Figure 5

Typical scans of background-subtracted neutron-scattering intensity vs $\hslash \omega$ in CuDCl at $T=1.9\text{K}$ showing the weak dispersion of magnetic excitation with $h$. Solid lines are the fits to the data as described in the text.