Kagome quantum spin systems in the atacamite family

Abstract: We present the hydrothermal synthesis, as well as structural and chemical analysis of single crystals on the compounds EuCu${3}$(OH)${6}$Cl${3}$, Zn${x}$Cu${4-x}$(OH)${6}$(NO${3}$)${2}$ and haydeeite, MgCu${3}$(OH)${6}$Cl${2}$ all arising from the atacamite family. Magnetic and specific-heat measurements down to 1.8 K are carried out for these systems. EuCu${3}$(OH)${6}$Cl${3}$ has a frustrated antiferromagnetic Cu$^{2+}$ ground state with order at 15 K, a strong anisotropy and increased magnetization from Van Vleck paramagnetic Eu$^{3+}$ contributions. ZnCu${3}$(OH)${6}$(NO${3}$)${2}$ reveals antiferromagnetic order at 9 K and measurements on haydeeite single crystals confirm the ferromagnetic order at 4.2 K with the easy axis within the kagome plane. These results prove that the atacamite family presents a broad class of materials with interesting magnetic ground states.