【学术视频】太赫兹电磁波与量子材料相互作用学术研讨会 | 中科院固体物理研究所苏付海研究员

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图 | 苏付海

题   目：Probing ultrafast photocarrier dynamics of 2D materials under high pressure

报告人：苏付海

单   位：中国科学院固体物理研究所

时   间：2019-11-16

地   点：上海大学

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报告摘要

The extremely conditions such as high magnetic field and pressure are essential to control the interplay of charge, spin and lattice degrees of freedom in materials. Hydrostatic pressure above gigapascal (GPa) magnitude created in a diamond anvil cell (DAC) can generate sizeable compressive strain in layered 2D materials such as Black phosphorus (BP), graphene, etc, and therefore allow for effective modifications of interlayer interaction, interatomic orbital coupling, lattice structure and carrier transport.  In this work, we will present some of our recent results for the pressure dependent photocarrier dynamics in 2D materials including multilayer BP, graphene, etc. Recently, we have carried out in situ measurements of optical pump-probe spectroscopy (OPPS) under high pressure above 12 GPa. As for BP, the OPPS is featured with a subpicosecond saturable absorption (SA) followed by a longitudinal coherent acoustic phonon (CAP) with lifetime of hundreds picoseconds below 10 GPa. However, the SA suddenly switches to strong absorption enhancement (AE) whilst the CAP disappears as further increasing pressure. The pressure behaviors of CAP reflect the pressure-driven enhancement of interlayer coupling along the cross-plane direction. However, the transition from SA to AE dynamics indicates the pressure induced in-plane carrier transport change.  In addition, we have combined the time-domain Terahertz (THz) spectroscopy and  DAC with 300-micrometers clear aperture, and developed high-pressure optical pump-THz probe method basing on Fraunhofer diffraction. We measured the transient photoconductivity with sub-picosecond time resolution for BP and graphene under high pressure, which demonstrated the feasibility to probe the carrier dynamics of high-pressure phase materials by time resolved THz spectroscopy. 

个人简介

苏付海，博士，研究员，硕士研究生导师。主要从事高压、强磁场等极端条件下新型超快光谱学技术发展以及低维半导体、强关联体系等材料的超快动力学研究。主持国家自然科学基金、中科院装备、基金委重大科研仪器子课题等多个项目。

会议简介

Terahertz spectroscopy uses far-infrared radiation to extract spectral information in an otherwise inaccessible portion of the electromagnetic spectrum. Materials research is an essential component of modern terahertz systems: novel, higher-power terahertz sources rely heavily on new materials such as quantum cascade structures, metallic spintronic heterostructures. At the same time, terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules. In recent years, the interaction of ultrafast THz spectroscopy and quantum materials research has blossomed into a vibrant branch of condensed matter science. This workshop was provided an open platform for the outstanding new questions and challenges in the THz and ultrafast spectroscopic technique and its applications to quantum materials. 

主办方：上海大学理学院物理系，上海大学量子与分子结构国际中心，上海大学材料基因组工程研究院，上海市高温超导重点实验室

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