Crystal structure, magnetic and resonant properties of decorated spin kagome system (CsCl)Cu${}_5$As${}_2$O${}_{10}$

We report the synthesis and investigation of the crystal structure and physical properties of the averievite-like arsenate, $(\mathrm{C}\mathrm{s}\mathrm{C}\mathrm{l}){\mathrm{C}\mathrm{u}}_5{\mathrm{A}\mathrm{s}}_2{\mathrm{O}}_{10}$. Just above room temperature, this compound undergoes a structural phase transition from the high-temperature trigonal $P\bar{3}m1$ $(a=b=a_0$ and $c=c_0)$ to the low-temperature monoclinic $I2\mathrm{/}a$ phase $(a\approx \sqrt{3}{a}_0$, $b=a_0$, $c\approx 2c_0$ and $\beta \approx {90.6}^{\circ })$. According to thermodynamic and nuclear magnetic resonance measurements, it experiences a phase transition into a canted antiferromagnetic state at $T_N=21\mathrm{K}$. The density functional theory calculations place the energy scale of kagome exchange interaction parameter in $(\mathrm{C}\mathrm{s}\mathrm{C}\mathrm{l}){\mathrm{C}\mathrm{u}}_5{\mathrm{A}\mathrm{s}}_2{\mathrm{O}}_{10}$ in between those in V- and P-analogs.