摘要
电子、晶格、自旋和轨道微观自由度对超导材料的宏观特性起到至关重要的作用.在超导体系中,特别是非常规超导材料,这些自由度衍生出具有不同能量尺度的玻色激发和有序态.前者如声子、磁振子、电荷密度波、自旋密度波、自旋涨落、向列涨落等;后者如超导态、赝能隙态、向列相、反铁磁/铁磁等.前者与后者的形成密切相关.尤其是,不同的玻色激发在频域内纠缠在一起彼此相互作用,同时又与电子(或准粒子)耦合,构建出复杂而又丰富的平衡态和非平衡态物理过程.超快光谱技术的独特性在于具有宽能量范围和高时间分辨率的特点,利用光(电磁波)与超导材料相互作用中的线性和非线性响应,可以共振或非共振地探测与调控这类材料中的准平衡或非平衡态动力学属性.因为桌面超快光谱系统功能全面且具有很大的灵活性,它不仅被应用于超导体系,而且被广泛应用于其他各种无机和有机材料.由于非平衡态理论,特别是与关联电子体系相关的,目前还处在快速发展的阶段,所以本综述主要介绍了常用的桌面超快光谱技术和目前被广泛使用的相关分析理论,聚焦于讨论超导材料中超快光谱实验数据涌现出来的一些普适性趋势及进展.所涉及的超导材料包含了常规超导体、铜氧化物超导体、铁基超导体和重费米子超导体.
The microscopic degrees of freedom of electron,lattice,spin and orbit play a vital role in the macroscopic properties of superconducting materials.In superconducting systems,especially unconventional superconducting materials,these degrees of freedom lead to enormous collective excitations and ordered states with different energy scales.Examples for the collective excitations are phonons,magnons,charge density waves,spin density waves,spin fluctuations,nematic fluctuations,and so on;ordered states are superconducting state,pseudogap state,nematic phase,antiferromagnetic/ferromagnetic order,and so on.The collective exciations can make vital contribution to the formation of the ordered states.In particular,different types of collective excitations are entangled in the frequency domain and interact with each other,and at the same time are coupled with electrons(or quasiparticles),resulting in the complex and rich physics in the equilibrium and non-equilibrium states.The uniqueness of ultrafast optical spectroscopy is that it covers both a wide energy range and high time resolution.Using the linear and nonlinear optical responses during the interaction between light(electromagnetic waves)and superconducting materials,the quasi-equilibrium or non-equilibrium dynamical properties can be detected and controlled at the resonant or non-resonant conditions.Because of the flexibility of the table-top optical systems,it is not only used in superconducting materials,but also widely employed in various other inorganic and organic material systems.Because the non-equilibrium theory,especially the theoretical research on correlated electronic materials,is still in the stage of rapid development,this review mainly introduces the commonly used table-top ultrafast optical spectroscopy and the related analytical theories that are currently widely used,focusing on discussion of the universal trends and developments emerging from experimental data of the ultrafast optical spectroscopy on superconducting materials,which include the conventional superconductors,cuprate superconductors,iron-based superconductors,and heavy fermion superconductors.
作者
齐静波
QI Jingbo(State Key Laboratory of Electronic Thin Films and Integrated Devices,University of Electronic Science and Technology of China,Chengdu 610054,China;School of Electronic Science and Engineering,University of Electronic Science and Technology of China,Dongguan 523808,China)
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2021年第4期41-74,共34页
Scientia Sinica Physica,Mechanica & Astronomica
基金
国家自然科学基金(编号:11974070,11734006)
广东东莞市核心技术攻关前沿项目(编号:2019622101004)
中国科学院交叉创新团队资助。
关键词
超快光谱
泵浦-探测
超导材料
非平衡态
ultrafast optical spectroscopy
pump-probe
superconducting materials
non-equilibrium state
