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arXiv 2602.04534cond-mat.mtrl-scicond-mat.str-el
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费米面几何和动量依赖的电子-声子耦合驱动准一维ZrTe₃中的电荷密度波

Fermi surface geometry and momentum dependent electron-phonon coupling drive the charge density wave in quasi-1D ZrTe$3$

Dipartimento di Fisica, Università di Trento(特伦托大学物理系)

Josu Diego, Matteo Calandra

AI总结:

研究揭示ZrTe₃中电荷密度波的起源是费米面几何与动量依赖的电子-声子耦合的协同作用,后者起主导作用。

摘要:

ZrTe₃是一种典型的准一维化合物,通过非常尖锐的柯恩反常在声子动量空间中经历电荷密度波相变。尽管费米面几何长期以来被认为是不稳定性的主要驱动力,但对晶格动力学和电子-声子作用的完整理解仍不清楚。我们的第一性原理计算显示,在高对称相中,只有当Te 5p轨道上的Hubbard相互作用被包括在内时,才能正确再现费米面,这反过来对于在CDW波矢处出现软谐振声子模式至关重要。分析模式和动量依赖性电子-声子耦合,我们发现其随声子动量的变化主导了电子效应。这些结果明确地将ZrTe₃中的CDW起源确定为费米面几何和动量依赖的电子-声子耦合的协同作用,后者起主导作用。我们进一步确定了低对称CDW相中的原子结构,揭示了非手性调制。本工作揭示的机制对其他准一维系统,包括三价硫化物和具有皮埃尔-利链结构的化合物具有直接相关性。

英文摘要:

ZrTe$_3$ is a prototypical quasi-one-dimensional compound undergoing a charge density wave transition via a very sharp Kohn anomaly in phonon momentum space. While Fermi surface geometry has long been considered the primary driver of the instability, a full understanding of the lattice dynamics and electron-phonon role has remained elusive. Our first principles calculations in the high-symmetry phase show that the Fermi surface is correctly reproduced only when the Hubbard interaction on the Te $5p$ orbitals is included, which in turn is essential for the appearance of a soft harmonic phonon mode at the CDW wavevector. Analyzing the mode and momentum dependence of the electron-phonon coupling, we find that its variations with phonon momentum dominate over electronic effects. These results identify unambiguously the CDW origin in ZrTe$_3$ as a cooperative effect of Fermi surface geometry and momentum-dependent electron-phonon coupling, with the latter playing the leading role. We further determine the atomic structure in the low-symmetry CDW phase, revealing a nonchiral modulation. The mechanisms revealed in our work are directly relevant to other quasi-1D systems, including trichalcogenides and compounds hosting Peierls-like chains.

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