Photoinduced Nonequilibrium Response in Underdoped YBa2Cu3O6+x

Abstract

Intense laser pulses have recently emerged as a tool to tune between different orders in complex quantum materials. Among different light-induced phenomena, transient superconductivity far above the equilibrium transition temperature in cuprates is particularly attractive. Key to those experiments was the resonant pumping of specific phonon modes, which was believed to induce superconducting phase coherence by suppressing the competing orders or modifying the structure slightly. Here, we present a comprehensive study of photo-induced nonequilibrium response in underdoped YBa 2 Cu 3 O 6+x . We find that upon photo-excitations, Josephson plasma edge in superconducting state is initially removed accompanied by quasiparticle excitations, and subsequently reappears at frequency lower than the static plasma edge within short time. In normal state, an enhancement or weaker edge-like shape is indeed induced by pump pulses in the reflectance spectrum accompanied by simultaneous rises in both real and imaginary parts of conductivity. We compare the pump-induced effects between near-and mid-infrared excitations and exclude phonon pumping as a scenario for the photo-induced effects above. We further elaborate the transient responses in normal state are unlikely to be explained by photoinduced superconductivity. arXiv:1904.10381v3 [cond-mat.supr-con]

Colloquium: Nonthermal pathways to ultrafast control in quantum materials

“…Among others, coherent control of the crystal lattice by driving to anharmonic regimes has been suggested as a mechanism to induce ultrafast phase transitions, such as a lattice-controlled metal-insulator transition (Rini et al, 2007), and lead to states of matter without equilibrium counterparts, including possible light-induced superconductivity (Fausti et al, 2011;Hu et al, 2014;Kaiser et al, 2014b;Mankowsky et al, 2014). In turn, these groundbreaking experiments have stimulated considerable theoretical activity on nonequilibrium superconductivity (Babadi et al, 2017;Coulthard et al, 2017;Dasari and Eckstein, 2018;Denny et al, 2015;Kennes et al, 2017;Kim et al, 2016;Knap et al, 2016;Komnik and Thorwart, 2016;Mazza and Georges, 2017;Murakami et al, 2017;Nava et al, 2018;Okamoto et al, 2016;Raines et al, 2015;Sentef, 2017;Sentef et al, 2016Sentef et al, , 2017Wang et al, 2018a), as well as a lively debate on how we should understand and interpret optical superconducting-like signatures on transient timescales (Demsar, 2020;Zhang et al, 2020). Furthermore, coherent optical driving of the lattice has been suggested as a path towards switching applications (see Sec.…”

Nonthermal pathways to ultrafast control in quantum materials

“…Among others, coherent control of the crystal lattice by driving to anharmonic regimes has been suggested as a mechanism to induce ultrafast phase transitions, such as a lattice-controlled metal-insulator transition (Rini et al, 2007), and lead to states of matter without equilibrium counterparts, including possible light-induced superconductivity (Fausti et al, 2011;Hu et al, 2014;Kaiser et al, 2014b;Mankowsky et al, 2014). In turn, these groundbreaking experiments have stimulated considerable theoretical activity on nonequilibrium superconductivity (Babadi et al, 2017;Coulthard et al, 2017;Dasari and Eckstein, 2018;Denny et al, 2015;Kennes et al, 2017;Kim et al, 2016;Knap et al, 2016;Komnik and Thorwart, 2016;Mazza and Georges, 2017;Murakami et al, 2017;Nava et al, 2018;Okamoto et al, 2016;Raines et al, 2015;Sentef, 2017;Sentef et al, 2016Sentef et al, , 2017Wang et al, 2018a), as well as a lively debate on how we should understand and interpret optical superconducting-like signatures on transient time scales (Demsar, 2020;Zhang et al, 2020).…”

Ultrafast optical spectroscopy of superconducting materials

“…Chu等 人 [63] 情况: 在BCS超导和d波超导都观察到了希格斯振幅 模, 表现为太赫兹高次谐波信号的产生. 超快光谱在超导体系上的研究, 由于一些问 题还处在前期探索或争议阶段, 所以本文没有触 及和展开, 特别是近几年涌现出的共振激发某类 声子模式引起的所谓"光致超导"或"光增强超导"现 象(Photo-Induced or Photo-Enhanced Superconductivity) [140][141][142] . 大型光源为基础的超快光谱, 如基于超 The microscopic degrees of freedom of electron, lattice, spin and orbit play a vital role in the macroscopic properties of superconducting materials.…”