论文标题
语音软模式和强大的电子背景行为在激子绝缘子TA $ _2 $ nise $ _5 $（带有Erratum）中的结构相变
Phononic soft mode and strong electronic background behavior across the structural phase transition in the excitonic insulator Ta$_2$NiSe$_5$ (with Erratum)
论文作者
论文摘要
ta $ _2 $ nise $ _5 $成为托管激子绝缘体基地状态最受调查的候选材料之一。许多研究将相应的相变为激发子的凝结，破坏了连续的对称性。最近，这一观点挑战了这一观点，指出了在结构相转换上与半导体 - 异位绝缘体过渡一起丢失两个镜子对称性的重要性。对于这种情况，提出了低能量的不稳定光区中心声子以驱动过渡。在这里，我们报告了使用拉曼光谱法对这种软模式行为进行实验观察。此外，我们发现了一种新型的光谱特征，该特征可能具有电子或关节电子和语音的起源，这显然与晶状体动力学明显不同，并且在TC上占主导地位。这表明了驱动相变的关节结构和电子顺序的图片。
Ta$_2$NiSe$_5$ became one of the most investigated candidate materials for hosting an excitonic insulator ground state. Many studies describe the corresponding phase transition as a condensation of excitons breaking a continuous symmetry. This view got challenged recently pointing out the importance of the loss of two mirror symmetries at a structural phase transition that occurs together with the semiconductor-excitonic insulator transition. For such a scenario an unstable optical zone-center phonon at low energy is proposed to drive the transition. Here we report on the experimental observation of such a soft mode behavior using Raman spectroscopy. In addition we find a novel spectral feature, likely of electronic or joint electronic and phononic origin, that is clearly distinct from the lattice dynamics and that becomes dominant at Tc. This suggests a picture of joint structural and electronic order driving the phase transition.
