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arXiv 2005.12768cond-mat.str-el
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关联半金属Nd2Ir2O7中的非常规自由电荷

Unconventional free charge in the correlated semimetal Nd2Ir2O7

K. Wang, B. Xu, C. W. Rischau, N. Bachar, B. Michon, J. Teyssier, Y. Qiu, T. Ohtsuki, Bing Cheng, N. P. Armitage, S. Nakatsuji, D. van der Marel

摘要:

Nd_2Ir_2O_7是一种具有烧绿石结构的相关半金属,其中竞争的自旋-轨道耦合和电子-电子相互作用被认为诱导了时间反演对称性破缺的Weyl半金属相,其特征在于费米能处的拓扑保护的Dirac点对。然而,这些材料中的涌现性质还远未清楚,并且已经发现了奇异的新物质状态。在这里,我们从光学上证明了在低温下自由载流子的光谱权重与T ^2成正比,这里T是温度,正如对无质量狄拉克电子的预期。然而,我们{ \em没有}观察到比热中相应的T^3项。该系统是不是在费米液体状态进一步证实了“普朗克”T-线性温度依赖的动量弛豫速率和相关诱导的间隙在低温下的逐步开放。这些观察结果不能调和的电子类准粒子的能带理论的框架内,指向有效的去耦的电荷输运从单粒子部门。

英文摘要:

Nd2Ir2O7 is a correlated semimetal with the pyrochlore structure, in which competing spin-orbit coupling and electron-electron interactions are believed to induce a time-reversal symmetry broken Weyl semimetal phase characterized by pairs of topologically protected Dirac points at the Fermi energy. However, the emergent properties in these materials are far from clear, and exotic new states of matter have been conjectured. Here we demonstrate optically that at low temperatures the free carrier spectral weight is proportional to T^2 where T is the temperature, as expected for massless Dirac electrons. However, we do {\em not} observe the corresponding T^3 term in the specific heat. That the system is not in a Fermi liquid state is further corroborated by the "Planckian" T-linear temperature dependence of the momentum relaxation rate and the progressive opening of a correlation-induced gap at low temperatures. These observations can not be reconciled within the framework of band theory of electron-like quasiparticles and point toward the effective decoupling of the charge transport from the single particle sector.

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