Antiferromagnetic phase transition in the <i>S</i>=3/2 hyperkagome manganate Zn₂Mn₃O₈

The hyperkagome lattice has attracted much attention due to a 3-dimensional corner-sharing triangle network. Since the discovery of the spin-liquid state of Na₄Ir₃O₈ in 2007, many theoretical studies on hyperkagome antiferromagnets have been published. However, few other model materials have been found. In this presentation, we report a novel hyperkagome antiferromagnet Zn₂Mn₃O₈, where Mn⁴⁺ (S=3/2) ions form a hyperkagome network. Magnetic susceptibility and heat capacity measurements for Zn₂Mn₃O₈ found an antiferromagnetic interaction with a Curie-Weiss temperature θ_CW = －54 K and an antiferromagnetic phase transition at 5.7 K, indicating the presence of the geometrical frustration. These results suggest that Zn₂Mn₃O₈ is the first hyperkagome antiferromagnet to show a phase transition. We will discuss the detailed behavior of this antiferromagnetic transition.