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Nodal-line semimetal HMTSF-TCNQ: Anomalous orbital diamagnetism and charge density wave
Physical Review B ( IF 3.2 ) Pub Date : 2021-10-25 , DOI: 10.1103/physrevb.104.155202
S. Ozaki 1 , I. Tateishi 1, 2 , H. Matsuura 1 , M. Ogata 1, 3 , K. Hiraki 4, 5
Affiliation  

This study investigates the electronic states and physical quantities of an organic charge-transfer complex HMTSF-TCNQ, which undergoes a charge-density-wave (CDW) phase transition at temperature Tc30 K. A first-principles calculation is utilized to determine that the normal state is a topological semimetal with open nodal lines. Based on the first-principles calculation, we develop a tight-binding model to investigate the electronic state in detail. Below Tc, the CDW phase is examined in the tight-binding scheme using the mean-field approximation. It is shown that the open nodal lines are deformed into closed ones, and their shapes are sensitive to the order parameter. Using this tight-binding model, we theoretically evaluate the temperature dependencies of two physical quantities: the spin-lattice relaxation time T1 and the orbital magnetic susceptibility. In particular, an anomalous plateau is obtained at low temperatures in the orbital diamagnetism. We conclude that this anomalous plateau originates owing to the conflict between the interband diamagnetism, impurity scattering, and the nodal-line deformation. We also conduct an experiment to investigate the orbital magnetism, and the results are in excellent quantitative agreement with the theory.

中文翻译:

节点线半金属 HMTSF-TCNQ:异常轨道抗磁性和电荷密度波

本研究调查了有机电荷转移复合物 HMTSF-TCNQ 的电子状态和物理量,该复合物在温度下经历电荷密度波 (CDW) 相变 C30 K. 利用第一性原理计算确定正常状态是具有开放节点线的拓扑半金属。基于第一性原理计算,我们开发了一个紧束缚模型来详细研究电子状态。以下C,使用平均场近似在紧束缚方案中检查 CDW 相位。结果表明,开放节点线变形为封闭节点线,其形状对阶次参数敏感。使用这种紧束缚模型,我们从理论上评估了两个物理量的温度依赖性:自旋晶格弛豫时间1和轨道磁化率。特别是,在轨道抗磁性的低温下获得了异常高原。我们得出结论,这个异常高原起源于带间抗磁性、杂质散射和节点线变形之间的冲突。我们还进行了一个实验来研究轨道磁性,结果与理论具有极好的定量一致性。
更新日期:2021-10-26
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