Scientific Reports ( IF 3.8 ) Pub Date : 2019-02-12 , DOI: 10.1038/s41598-018-36123-7 Kazuki Iida 1 , Hiroyuki Yoshida 2 , Hirotaka Okabe 3 , Naoyuki Katayama 4 , Yuto Ishii 2 , Akihiro Koda 3, 5 , Yasuhiro Inamura 6 , Naoki Murai 6 , Motoyuki Ishikado 1 , Ryosuke Kadono 3, 5 , Ryoichi Kajimoto 6
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Molecular based spin-1/2 triangular lattice systems such as LiZn2Mo3O8 have attracted research interest. Distortions, defects, and intersite disorder are suppressed in such molecular-based magnets, and intrinsic geometrical frustration gives rise to unconventional and unexpected ground states. Li2AMo3O8 (A = In or Sc) is such a compound where spin-1/2 Mo3O13 clusters in place of Mo ions form the uniform triangular lattice. Their ground states are different according to the A site. Li2InMo3O8 undergoes conventional 120° long-range magnetic order below TN = 12 K whereas isomorphic Li2ScMo3O8 exhibits no long-range magnetic order down to 0.5 K. Here, we report exotic magnetisms in Li2InMo3O8 and Li2ScMo3O8 investigated by muon spin rotation (μSR) and inelastic neutron scattering (INS) spectroscopies using polycrystalline samples. Li2InMo3O8 and Li2ScMo3O8 show completely different behaviors observed in both μSR and INS measurements, representing their different ground states. Li2InMo3O8 exhibits spin wave excitation which is quantitatively described by the nearest neighbor anisotropic Heisenberg model based on the 120° spin structure. In contrast, Li2ScMo3O8 undergoes short-range magnetic order below 4 K with quantum-spin-liquid-like magnetic fluctuations down to the base temperature. Origin of the different ground states is discussed in terms of anisotropies of crystal structures and magnetic interactions.
中文翻译:

均匀三角晶格中的量子磁性 Li 2 A Mo 3 O 8 ( A = In, Sc)
基于分子的自旋1/2三角晶格系统例如LiZn 2 Mo 3 O 8引起了研究兴趣。在这种基于分子的磁体中,扭曲、缺陷和位点间无序被抑制,并且内在的几何挫败会产生非常规和意想不到的基态。 Li 2 A Mo 3 O 8 ( A =In或Sc)是这样的化合物,其中自旋1/2 Mo 3 O 13簇代替Mo离子形成均匀的三角形晶格。根据 A 位点,它们的基态有所不同。 Li 2 InMo 3 O 8在T N = 12 K 以下经历传统的 120° 长程磁序,而同质 Li 2 ScMo 3 O 8在低至 0.5 K 时不表现出长程磁序。在这里,我们报告了 Li 2中的奇异磁性使用多晶样品通过μ子自旋旋转( μSR )和非弹性中子散射(INS)光谱研究InMo 3 O 8和Li 2 ScMo 3 O 8 。 Li 2 InMo 3 O 8和Li 2 ScMo 3 O 8在μ SR 和INS 测量中观察到完全不同的行为,代表它们不同的基态。 Li 2 InMo 3 O 8表现出自旋波激发,这可以通过基于120°自旋结构的最近邻各向异性海森堡模型定量描述。 相比之下,Li 2 ScMo 3 O 8经历低于4 K的短程磁序,并在低至基础温度时出现类似量子自旋液体的磁涨落。从晶体结构的各向异性和磁相互作用的角度讨论了不同基态的起源。