AI 中文总结
本研究通过低温磁性测量与⁷Li NMR表征，揭示无序三角晶格化合物LCYBO具有孤立J_eff=1/2 Kramer双重态及短程关联磁性，确立其为结构无序的阻挫三角晶格磁体。
AI 中文摘要
几何阻挫、自旋-轨道耦合与结构无序的相互作用可在稀土三角晶格磁体中产生非常规磁性基态。我们报道对无序三角晶格化合物LiCaYb₅(BO₃)₆（LCYBO）的低温磁性与⁷Li核磁共振（NMR）研究。Rietveld精修确认其为六方晶系P6₅22结构，存在部分Ca/Yb反位无序及分数占据的Li位。磁化率与磁化强度测量表明，该体系具有孤立性良好的有效J_eff=1/2 Kramer双重态，且存在弱反铁磁相互作用（θ_CW≈-0.54 K）。比热在0.43 K附近呈现弱异常，表明体系发展出短程关联磁性，而非常规长程有序。⁷Li NMR谱随冷却显著展宽，与内部磁场不均匀性增强一致。自旋-晶格弛豫呈现两个弛豫分量，与反位无序及竞争交换路径导致的局域磁环境分布相符。本研究确立LCYBO为结构无序的阻挫三角晶格磁体，具有关联的低能自旋动力学。
英文摘要
The interplay between geometric frustration, spin--orbit coupling, and structural disorder can give rise to unconventional magnetic ground states in rare-earth triangular-lattice magnets. We report low-temperature magnetic and $^7$Li NMR investigations of the disordered triangular-lattice compound LiCaYb$_5$(BO$_3$)$_6$ (LCYBO). Rietveld refinement confirms a hexagonal $P6_522$ structure with partial Ca/Yb antisite disorder and fractional Li occupancy. Magnetic susceptibility and magnetization measurements indicate a well-isolated effective $J_{\mathrm{eff}}=1/2$ Kramers doublet with weak antiferromagnetic interactions ($θ_{\mathrm{CW}} \approx -0.54$~K). The specific heat reveals a weak anomaly near 0.43 K, suggesting the development of short-range correlated magnetism rather than conventional long-range order. $^7$Li NMR spectra broaden strongly upon cooling, consistent with increasingly inhomogeneous internal magnetic fields. The spin-lattice relaxation exhibits two relaxation components consistent with disorder-induced distributions of local magnetic environments arising from antisite disorder and competing exchange pathways. Our results establish LCYBO as a structurally disordered frustrated triangular-lattice magnet with correlated low-energy spin dynamics.
Comments13 Pages, 10 figures
