Magnetic excitation and local magnetic susceptibility of the excitonic insulator Ta2NiSe5 investigated by 77Se NMR
Magnetic excitation and local magnetic susceptibility of the excitonic insulator Ta2NiSe5 investigated by 77Se NMR
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77Se NMR 研究激子绝缘体 Ta2NiSe5 的磁激励和局域磁化率
DOI：
10.1103/physrevb.97.165127
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
and M. Itoh
中科院分区：
文献类型：
--
作者：
S. Li;S. Kawai;Y. Kobayashi;and M. Itoh
对多晶和单晶样品进行了核磁共振测量，以阐明的局域磁化率和磁激发，认为它经历了激子凝聚伴随着结构转变。我们确定了三个Se位的Knight Shift张量，并根据Se位的对称性分析了它们的各向异性。根据双链和二维三带模型计算的自旋极化率和轨道极化率，讨论了奈特位移与温度的关系。通过对转移的超精细耦合常数的分析，估计了由于Ni键和Seorbitals之间的混合而产生的大部分Seororal极化。原子核的自旋-晶格弛豫速率在其正下方没有出现相干峰，并且服从自旋能隙能与热激活温度的依赖关系。这一行为是根据激子绝缘体的三链Hubbard模型的理论研究提出的，它监视激子凝聚。
NMR measurements were made on polycrystalline and single-crystalline samples to elucidate local magnetic susceptibility and magnetic excitation of, which is proposed to undergo an exciton condensation accompanied by a structural transition at. We determine theKnight shift tensors for the three Se sites and analyze their anisotropy based on the site symmetry. The temperature dependence of the Knight shift is discussed on the basis of spin and orbital susceptibilities calculated for two-chain and two-dimensional three-band models. The large fraction of the Seorbital polarization due to the mixing between Niand Seorbitals is estimated from the analysis of the transferred hyperfine coupling constant. Also the nuclear spin-lattice relaxation rateis found not to show a coherent peak just belowand to obey the thermally activated temperature dependence with a spin gap energy of. This behavior ofmonitors the exciton condensation as proposed by the theoretical study ofbased on the three-chain Hubbard model for the excitonic insulator.