论文标题
三维狄拉克半学候选ir $ _2 $ in $ _8 $ se的线性频率光电电导率
Linear-in-Frequency Optical Conductivity over a broad range in the three-dimensional Dirac semimetal candidate Ir$_2$In$_8$Se
论文作者
论文摘要
新的DIRAC半学候选$ _2 $ in $ _8 $ se的光电电导率以40至30000 cm $^{ - 1} $在300 K下降到10 k的频率范围内测量。测量表明，该化合物是低载体密度金属的。我们发现，电导率的实际部分$σ_1（ω）$在300 K时在500至4000 cm $^{ - 1} $的频率上是线性的，并且随冷却而变化。这种线性强烈表明存在三维线性电子带，带有带横梁附近的频带。频带结构计算表明存在II型狄拉克点。通过将我们的数据与从频带结构计算出的光学电导率进行比较，我们得出结论，观察到的线性依赖性主要起源于狄拉克锥以及狄拉克锥和下一个下部频段之间的过渡。另外，在反射率光谱中，弱的能隙特征在电荷密度波相变温度以下解决。电子敏感性功能中确定了由不完美的费米表面嵌套产生的增强结构，表明费米表面嵌套驱动的不稳定性。
The optical conductivity of the new Dirac semimetal candidate Ir$_2$In$_8$Se is measured in a frequency range from 40 to 30000 cm$^{-1}$ at temperatures from 300 K down to 10 K. The measurement reveals that the compound is a low carrier density metal. We find that the real part of the conductivity $σ_1(ω)$ is linear in frequency over a broad range from 500 to 4000 cm$^{-1}$ at 300 K and varies slightly with cooling. This linearity strongly suggests the presence of three-dimensional linear electronic bands with band crossings near the Fermi level. Band structure calculations indicate the presence of type-II Dirac points. By comparing our data with the optical conductivity computed from the band structure, we conclude that the observed linear dependence mainly originates from the Dirac cones and the transition between the Dirac cones and the next lower bands. In addition, a weak energy gap feature is resolved below the charge density wave phase transition temperature in reflectivity spectra. An enhanced structure arising from the imperfect Fermi surface nesting is identified in the electronic susceptibility function, suggesting a Fermi surface nesting driven instability.
