论文标题
通过高谐波光谱法探测石墨烯中语音驱动的对称变化
Probing phonon-driven symmetry alterations in graphene via high-harmonic spectroscopy
论文作者
论文摘要
高谐波光谱已成为探测具有亚周期时间分辨率的固体中各种超快电子过程的重要成分。尽管具有极大的重要性，但高谐波光谱对固体中的声子动力学的敏感性并不众所周知。这项工作解决了这个关键问题，并证明了高谐波光谱在探测固体中相互交织的声子电子动力学中的潜力。泵脉冲激发单层石墨烯中的平面内光声子模式，并采用圆形极化脉冲来探测产生高阶谐波的激发声子动力学。我们表明，连贯的声子动力学改变了石墨烯与探针脉冲的动力对称，并导致对称性 - 孔子谐波的世代。此外，与突出的谐波峰相关的边带是由于相干动力学而产生的。发现激发声子模式的对称性和特征时间尺度决定了这些边带的极化和位置。目前的工作开放了具有子循环时间分辨率的固体中语音驱动过程和动力对称性的时间分辨探测的途径。
High-harmonic spectroscopy has become an essential ingredient in probing various ultrafast electronic processes in solids with sub-cycle temporal resolution. Despite its immense importance, sensitivity of high-harmonic spectroscopy to phonon dynamics in solids is not well known. This work addresses this critical question and demonstrates the potential of high-harmonic spectroscopy in probing intertwined phonon-electron dynamics in solids. A pump pulse excites in-plane optical phonon modes in monolayer graphene and a circularly polarised pulse is employed to probe the excited phonon dynamics that generates higher-order harmonics. We show that the coherent phonon dynamics alters the dynamical symmetry of graphene with the probe pulse and leads the generations of the symmetry-forbidden harmonics. Moreover, sidebands associated with the prominent harmonic peaks are generated as a result of the coherent dynamics. It is found that the symmetries and the characteristic timescale of the excited phonon mode determine the polarisation and positions of these sidebands. Present work opens an avenue in time-resolved probing of phonon-driven processes and dynamical symmetries in solids with sub-cycle temporal resolution.
