Li Boqiang, Wan Zongtang, Song Yiru, Ma Zhaohua, Zhao Yuqian, Wang Junfeng, Li Yuesheng
Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, 430074 Wuhan, People's Republic of China.
J Phys Condens Matter. 2023 Sep 15;35(50). doi: 10.1088/1361-648X/acf74e.
We propose the newly synthesized-BaNi(VO)(OH)(space group:R3‾m) as a candidate for the spin-1 kagome Heisenberg antiferromagnet (KHA). The compound features a uniform kagome lattice of Ni(= 1) ions with a large interlayer distance. High-field measurements at low temperatures reveal a susceptibility local minimum at ∼9 T, resembling a 1/3 magnetization plateau as predicted by the pure= 1 KHA model. Below ∼6 K, approximately 1% of the spins exhibit spin-glass order, which may be attributed to the nanocrystalline grain size of ∼50 nm. Despite the antiferromagnetic exchange coupling strength of ∼7 K, the majority of spins remain disordered down to ∼0.1 K as indicated by the observed power-law behaviors in magnetic specific heatCm∝T1.4. Our results demonstrate that the low-energy magnetic excitations in-BaNi(VO)(OH)are gapless, which contradicts the current theoretical expectations of the ideal model.
我们提出新合成的 BaNi(VO)(OH)（空间群：R3‾m）作为自旋-1 Kagome 海森堡反铁磁体（KHA）的候选材料。该化合物具有由 Ni(= 1) 离子构成的均匀 Kagome 晶格，且层间距较大。低温下的高场测量显示，在约 9 T 处磁化率出现局部最小值，类似于纯自旋-1 KHA 模型预测的 1/3 磁化平台。在约 6 K 以下，约 1% 的自旋呈现自旋玻璃序，这可能归因于约 50 nm 的纳米晶粒尺寸。尽管反铁磁交换耦合强度约为 7 K，但如磁比热 Cm∝T1.4 中观察到的幂律行为所示，大多数自旋在降至约 0.1 K 时仍保持无序状态。我们的结果表明，BaNi(VO)(OH) 中的低能磁激发是无隙 的，这与理想模型目前的理论预期相矛盾。
