Mirror symmetry breaking in a model insulating cuprate

Torre, A. de la; Seyler, Kyle L.; Zhao, Liuyan; Matteo, S. Di; Scheurer, Mathias S.; Li, Yangmu; Yu, Bin; Greven, M.; Sachdev, Subir; Norman, M. R.; Hsieh, David

doi:10.1038/s41567-021-01210-6

Cited by 32 publications

(8 citation statements)

References 40 publications

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“…(a detailed description is presented in the Supporting Information, Figure S16, Supporting Information). [40] As shown in Figures 3a and 4a, the SHG signals of HfGe 0.92 Te deviated from the EQ fitting. Therefore, the observed strong second-order surface nonlinearity most likely originated from the ED effect rather than from the EQ effect.…”

Section: Resultsmentioning

confidence: 81%

Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe_0.92Te

Zhao,

Chen,

Liang

et al. 2024

Advanced Materials

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Surface nonlinear optics are essential for developments in integrated photonics and micro/nano optoelectronics. However, the nonlinear optical conversion efficiency on a surface is restricted by the finite nonlinear susceptibility of matter and the intrinsic atomic‐layered interaction length between light and matter. In this work, based on an angular engineering strategy, we demonstrated that the centrosymmetric topological semimetal HfGe0.92Te crystal has a giant and anisotropic surface second‐order nonlinear susceptibility up to 5535±308 pm·V−1 and exhibits efficient and unprecedented second‐harmonic generation (SHG). The maximum optical conversion efficiency was found to be up to 3.75‰, which is 104 times higher than that obtained from a silicon surface. Because of the linear dispersion over a wide range of energies around the Dirac points, this high conversion efficiency can be maintained with SHG wavelengths ranging from the visible region (779 nm) to the deep‐ultraviolet region (257.5 nm). Our study can facilitate the development of topological photonics and integrated nonlinear photonics based on topological semimetals.This article is protected by copyright. All rights reserved

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Section: Resultsmentioning

confidence: 81%

Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe_0.92Te

Zhao,

Chen,

Liang

et al. 2024

Advanced Materials

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“…In particular, second harmonic generation (SHG) is sensitive to the inversion symmetry breaking in lattice or magnetic structure of quantum materials, which has become a crucial tool for characterizing structural, electronic, and magnetic properties associated with inversionsymmetry-breaking. [31][32][33][34][35][36][37] More significantly, much progress has been made on various time-resolved nonlinear spectroscopy techniques, particularly at low energies, enabling to probe the HHG signals using the time-domain THz scheme or to detect the photo-induced change of HHG after excitations. Those new developments have advanced the research field of exploring the exotic states of certain quantum materials, for example, detecting Higgs modes in superconductors, and tracking lightinduced phase-transitions in different quantum materials.…”

Section: Brief Introduction To Optical Spectroscopymentioning

confidence: 99%

Recent Development of Ultrafast Optical Characterizations for Quantum Materials

2022

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or far-infrared energy region are therefore of particular importance, for the THz frequencies (1 THz≈4.1 meV) are close to the energy scales of a number of important single-particle and collective excitations of quantum material systems, for example, pairing energy gaps of superconductors, lattice vibration modes (phonons), collective spin waves (magnons), Josephson plasmon in high temperature superconductors, and binding energy of bound electron-hole pairs (excitons), [1] and they are linked to a large number of fundamental physical problems currently under intensive investigations in condensed matter physics. The information yielded from equilibrium optical measurements are usually prerequisites for understanding the nonequilibrium optical properties probed by ultrafast time-resolved spectroscopy techniques.In the last three decades, we have witnessed a rapid development in ultrafast laser and nonlinear optical techniques. The intense ultrashort optical pulses at wavelengths spanning the electromagnetic spectrum from terahertz through visible to X-ray have been generated from table-top laser sources and free-electron laser facilities. A variety of time-resolved spectroscopy techniques on the basis of pump-probe scheme have been developed. Depending on the fluence of pump pulses, photoexcitations can induce different effects and phenomena. For sufficiently weak perturbations, the photoexcitation of charge carriers does not change the free-energy landscape and the system relaxes back to the equilibrium state in a short time scale. The relaxation process is determined by the same interactions (e.g for example, electron-electron, electron-phonon) that govern the equilibrium properties. In principle, one can extract the coupling strength of electron to other degrees of freedom from the relaxation dynamics. In addition, the ultrashort laser pulse whose duration is shorter than the periodicity of targeted lattice/spin modes can trigger coherent oscillations at the corresponding frequencies of collective modes, for example, phonon, magnon, etc. with decay times that are related to the dephasing times. This enables one to detect collective-mode excitations that may not be easily accessed to or probed by other techniques.By contrast, with strong pump pulses, the photoexcitation can excite a sufficient number of electrons or drive the motion of collective mode to a large amplitude. The corresponding perturbation to the lattice/spin degrees of freedom can be large enough to modify the free-energy landscape. As a result, The advent of intense ultrashort optical pulses spanning a frequency range from terahertz to the visible has opened a new era in the experimental investigation and manipulation of quantum materials. The generation of strong optical field in an ultrashort time scale enables the steering of quantum materials nonadiabatically, inducing novel phenomenon or creating new phases which may not have an equilibrium counterpart. Ultrafast time-resolved optical techniques have provided rich information and played an im...

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“…Especially, nonlinear responses yield rich information such as symmetry and geometric properties of quantum phases [1]. For example, the second-order optical response is a useful tool for probing the microscopic parity breaking in complex ordered states because the second-order response requires broken inversion symmetry due to the symmetry constraint [2,3]. Furthermore, in the application field, the nonlinear response is expected to be a new basis of the photo-electron converter.…”

Section: Introductionmentioning

confidence: 99%

“…In the multiferroic materials science, indeed, the second harmonic generation has been introduced as a probe for magnetic structures [4]. Moreover, the second harmonic generation experiments have revealed exotic states breaking the symmetry in correlated electron systems such as cuprate high-temperature superconductors [2,3].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear optical responses in noncentrosymmetric superconductors

Tanaka¹,

Watanabe²,

Yanase³

2022

Preprint

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The unique nonreciprocal responses of superconductors, which stem from the Cooper pairs' quantum condensation, have been attracting attention. Recently, theories of the second-order nonlinear response in noncentrosymmetric superconductors were formulated based on the Bogoliubov-de Gennes theory. In this paper, we study the mechanism and condition for second-order optical responses of time-reversal symmetric superconductors. The numerical results show the characteristic photocurrent and second harmonic generation in the superconducting state. However, the superconductivity-induced nonlinear optical responses disappear under some conditions on pair potential. We show that the coexistence of intraband and interband pairing is necessary for the second-order superconducting optical responses. In addition, the superconducting Berry curvature factor, which is related to a component of Berry curvature in the superconducting state, is essential for the nonlinear responses. Thus, we derived the microscopic conditions where the superconducting nonlinear response appears.

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Mirror symmetry breaking in a model insulating cuprate

Cited by 32 publications

References 40 publications

Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe_0.92Te

Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe_0.92Te

Recent Development of Ultrafast Optical Characterizations for Quantum Materials

Nonlinear optical responses in noncentrosymmetric superconductors

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Mirror symmetry breaking in a model insulating cuprate

Cited by 32 publications

References 40 publications

Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe0.92Te

Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe0.92Te

Recent Development of Ultrafast Optical Characterizations for Quantum Materials

Nonlinear optical responses in noncentrosymmetric superconductors

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Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe_0.92Te

Angular Engineering Strategy for Enhanced Surface Nonlinear Frequency Conversion in Centrosymmetric Topological Semimetal HfGe_0.92Te