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arXiv 2602.09727cond-mat.mtrl-scicond-mat.str-el
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压力依赖的Ta₂Se硫化物拓扑、超导、光电和热物理性质:理论洞察

Pressure dependent topological, superconducting, optoelectronic and thermophysical properties of Ta2Se chalcogenide: Theoretical insights

Department of Physics, University of Rajshahi(拉杰沙希大学物理系)

Tauhidur Rahman, Jubair Hossan Abir, Sourav Kumar Sutradhar, Sraboni Saha Moly, Mst. Maskura Khatun, Md. Asif Afzal, Saleh Hasan Naqib

AI总结:

本研究通过理论分析揭示Ta₂Se在压力下的拓扑、超导、光电和热物理性质,发现压力可增强晶格稳定性并调节超导性能。

摘要:

四方Ta₂Se是一种层状、Ta丰富的硫化物,它不同于常规的MX₂过渡金属二硫化物,因为它具有密集的Ta-Ta网络,其顶部被Se方形网络层所覆盖。在这里,我们对Ta₂Se在0到10 GPa的水压调节进行了统一的原位原理研究,将结构响应、机械稳定性、热物理指标、键合演变、电子和光学行为、晶格动力学和超导性整合在一个框架内。所得的热物理描述符证实了压力强化的晶格:密度增加,德拜温度升高,熔点升高,最小热导率增加,而格鲁内斯坦参数保持在狭窄窗口内,表明没有异常的非谐振软化。键群指标和电子密度差分析揭示了一种混合金属-共价键合图景,主要由坚固的Ta-Ta金属主干主导,伴随压力强化的Ta-Se杂化。电子结构计算显示在压缩下保持金属性;压力拓宽带,减少费米能级处的态密度,重塑费米面,并指向可能的利夫希茨型重构,而无对称性破坏。光学响应保持金属性,具有类似德鲁德的低能行为和压力可调的光谱特征。声子色散谱无虚频,证实了动力学稳定性。电子-声子耦合计算将Ta₂Se分类为弱耦合、声子介导的超导体,临界温度约为3.9 K,与现有实验一致,并确立压力作为该金属丰富的层状平台中稳定性和超导相关描述符的实用控制手柄。

英文摘要:

Tetragonal Ta2Se is a layered, Ta-rich chalcogenide that departs from conventional MX2 transition-metal dichalcogenides by hosting dense Ta-Ta networks capped by Se square-net layers. Here, we present a unified first-principles investigation of hydrostatic-pressure tuning in Ta2Se from 0 to 10 GPa, connecting the structural response, mechanical stability, thermophysical indicators, bonding evolution, electronic and optical behavior, lattice dynamics and superconductivity within a single framework. The derived thermophysical descriptors corroborate a pressure-stiffened lattice: density increases, Debye temperature rises, melting temperature is elevated and minimum thermal conductivity increases, whereas the Grüneisen parameter remains within a narrow window, suggesting no anomalous anharmonic softening. Bond population metrics and electron-density-difference analysis revealed a mixed metallic-covalent bonding picture dominated by a robust Ta-Ta metallic backbone, accompanied by pressure-strengthened Ta-Se hybridization. Electronic-structure calculations show persistent metallicity under compression; pressure broadens bands, reduces density of states at the Fermi level, reshapes the Fermi surface and points to a possible Lifshitz-type reconstruction without symmetry breaking. The optical response remained metallic with Drude-like low-energy behavior and pressure-tunable spectral features. The phonon dispersions exhibit no imaginary modes, confirming dynamical stability. Electron-phonon coupling calculations classify Ta2Se as a weak-coupling, phonon-mediated superconductor with Tc around 3.9 K, consistent with available experiments and establish pressure as a practical control knob for stability and superconductivity-relevant descriptors in this metal-rich layered platform.

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