标题： 狄拉克半金属中高频模的非平凡声子动力学和显著的电子-声子耦合 显示英文标题

标题： Non-trivial phonon dynamics and significant electron-phonon coupling of the high frequency modes in a Dirac semimetal

摘要： 使用有限温度拉曼光谱，我们在不同频率范围内研究了狄拉克半金属Cd3As2中的电子-声子相互作用（EPI）和声子-声子散射动力学。在200 K以下，几乎所有声子模式的拉曼位移都出现显著软化，与标准非谐行为有明显偏差。实验观察到的拉曼线宽似乎可以通过EPI（在低温下相关）和声子-声子散射（在高温下占主导）的组合很好地描述，导致线宽的热演化中出现可观察到的极小值。虽然这一特征在最高频率的拉曼模式（196 cm-1）中最明显，但其强度随着拉曼频率的降低而逐渐减弱。通过声子自能计算高、低频模式的电子贡献，显示其定性地模仿了实验观察结果。发现声子诱导的带间散射导致声子线宽中存在一个极大值，该极大值关键取决于化学势的有限性。 显示英文摘要

摘要： Using finite temperature Raman spectroscopy, we investigate the electron-phonon interactions (EPI) and phonon-phonon scattering dynamics in the Dirac semimetal Cd3As2 in different fre quency regimes. Strong softening of the Raman shifts below 200 K is observed for almost all the phonon modes with a marked deviation from the standard anharmonic behavior. The experimen tally observed Raman linewidth seems to be captured well by a combination of EPI, relevant at low temperature (LT) and phonon-phonon scattering, which is predominant at high temperatures (HT), leading to an observable minima in the thermal evolution of the linewidth. While this fea ture is most prominently observed in the highest-frequency Raman mode (196 cm-1), its intensity gradually diminishes as the Raman frequency decreases. Computation of the electronic contribution to the phonon linewidth, for both the high and low frequency modes, from the phonon self-energy shows that it qualitatively mimics the experimental observations. It is found that phonon-induced interband scattering results in the presence of a maxima in phonon linewidth that crucially depends on the finiteness of the chemical potential.