Title: Synthesis and characterization of the novel breathing pyrochlore compound Ba3Tm2Zn5O11 Show Chinese title

Title: 新型呼吸式钙钛矿化合物 Ba₃Tm₂Zn₅O₁₁ 的合成与表征

Abstract: In this study, a novel material from the rare-earth based breathing pyrochlore family, Ba3Tm2Zn5O11, was successfully synthesized. Powder x-ray diffraction and high-resolution powder neutron diffraction confirmed phase purity and the F-43m breathing pyrochlore crystal structure, while thermogravimetric analysis revealed incongruent melting behavior compared to its counterpart, Ba3Yb2Zn5O11. High-quality single crystals of Ba3Tm2Zn5O11 were grown using the traveling solvent floating zone technique and assessed using Laue x-ray diffraction and single crystal x-ray diffraction. Thermodynamic characterization indicated paramagnetic behavior down to 0.05 K, and inelastic neutron scattering measurements identified distinct dispersionless crystal electric field energy bands, with the fitted crystal electric field model predicting a single-ion singlet ground state and an energy gap of ~9 meV separating it from the first excited (singlet) state. Additional low-energy excitation studies on single crystals revealed dispersionless bands at 0.8 and 1 meV. Computed phonon dispersions from first-principles calculations ruled out phonons as the origin of these modes, further illustrating the puzzling and unique properties of Ba3Tm2Zn5O11. Show Chinese abstract

Abstract: 本研究成功合成了来自稀土基呼吸型钙钛矿家族的一种新型材料 Ba3Tm2Zn5O11。 粉末 X 射线衍射和高分辨率粉末中子衍射证实了其相纯度及 F-43m 呼吸型钙钛矿晶体结构，而热重分析显示其与同类材料 Ba3Yb2Zn5O11 相比表现出不一致的熔化行为。 采用行波溶剂浮区法成功生长出高质量的 Ba3Tm2Zn5O11 单晶，并通过劳厄 X 射线衍射和单晶 X 射线衍射进行了评估。 热力学表征表明其顺磁性行为可延续至 0.05 K，非弹性中子散射测量确定了无色散的晶体电场能量带，拟合的晶体电场模型预测其具有单离子基态多重态以及约 9 meV 的能量间隙将其与第一激发（基态）态分开。 单晶上的额外低能激发研究表明存在 0.8 和 1 meV 的无色散带。 基于第一性原理计算得出的声子色散排除了这些模式由声子引起的可能性，进一步揭示了 Ba3Tm2Zn5O11 的令人费解的独特性质。