We report on the low-energy dynamics in the kagome antiferromagnet CaCu₃(OD)₆Cl₂∙0.6D₂O (Ca-kapellasite) as studied by use of ²D-NMR measurements. Previous ³⁵Cl-NMR measurements revealed that the nuclear spin–lattice relaxation rate (1/T₁) shows two peaks at temperatures, T^* = 7.2 K and T_s \( \simeq \) 25 K. While the low-temperature peak at T^* is ascribed to the critical fluctuations near the long-range magnetic ordering, the origin of the high-temperature peak has not been fully understood. From the 1/T₁ measurements on the D sites at the OD groups (D_OD), we find no peak at T_s, evidencing that the high-temperature peak is not related to the molecular dynamics of the OD groups. We discuss the possibility of a frustration-induced short-range ordered state below T_s before the long-range order is stabilized by the Dzyaloshinskii–Moriya interaction. We also observed static internal fields at the D_OD site in the long-range ordered state below T^*, and confirm the previously proposed negative-chirality q = 0 magnetic structure.

中文翻译：

---

S = 1/2 Kagome反铁磁体CaCu3（OD）6Cl2∙0.6D2O中受挫的短程有序出现在长程之上

我们报告了使用² D-NMR测量研究的kagome反铁磁体CaCu ₃（OD）₆ Cl ₂ ∙0.6D ₂ O（Ca-kapellasite）的低能动力学。之前的^35次Cl-NMR测量表明，核自旋-晶格弛豫速率（1 / T ₁）在温度T ^* = 7.2 K和T _s时显示两个峰_。 \（\ simeq \）25K。虽然T ^*处的低温峰是由于远距离磁有序附近的临界波动引起的，但高温峰的起源尚未完全明了。从在OD组（D _OD）的D位点进行的1 / T ₁测量，我们在T _s上没有发现峰，这表明高温峰与OD组的分子动力学无关。我们讨论了由Dzyaloshinskii-Moriya相互作用稳定远距离有序之前，在T _s以下受挫折诱导的近距离有序状态的可能性。我们还观察到D _OD处的静态内部场在低于T ^*的远距离有序状态下，确定先前提出的负手性q = 0磁性结构。