Interplay between nematicity and Bardasis-Schrieffer modes in the short-time dynamics of unconventional superconductors

Müller, Marvin A.; Volkov, Pavel A.; Paul, I.; Eremin, I.

doi:10.1103/physrevb.103.024519

Cited by 8 publications

(9 citation statements)

References 65 publications

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“…As was shown previously in Ref. 47 this mode corresponds to the fluctuations in ∆ d , which, in linear approximation, is the relative phase between the s-wave field and the d-wave field. The corresponding propagator has the form…”

Section: Effective Actionsupporting

confidence: 69%

“…Its possible experimental observation in the ironbased superconductors due to the close competition between the s ± ground state and the nearby d x 2 −y 2 instability [36][37][38][39][40][41] has triggered further theoretical interest in the properties of this mode 32,[42][43][44][45][46] . Furthermore, it was shown that the nearby nematic instability, if present, couples to the Bardasis-Schrieffer mode and pushes the resulting hybridized Bardasis-Schrieffernematic mode further below the quasiparticle continuum and extends the potential observability of this mode beyond the near-degeneracy region of the d-wave and s-wave superconducting states 47 In this manuscript we investigate theoretically the signatures of the Bardasis-Schrieffer mode in the third-harmonic generated current once the driving frequency matches the resonance condition 2Ω = ω BS . We show that the strength of the Bardasis-Schrieffer mode signal is of similar strength as the charge density fluctuations even in the clean limit making its observation a straightforward experimental task.…”

Section: Introductionmentioning

confidence: 99%

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Signatures of Bardasis-Schrieffer mode excitation in third-harmonic generated currents

Müller

Eremin

2021

Phys. Rev. B

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We theoretically analyze the collective modes in unconventional superconductors focusing on Bardasis-Schrieffer (BS) mode and its contribution to the third harmonic generation currents. Starting from a model with competing superconducting pairing instabilities we add fluctuations of the fields beyond saddle point approximation and calculate their response to an applied pulsed electric field. To model phase fluctuations appropriately we take into account the effect of the long-range Coulomb interaction. While the phase mode is pushed into a plasmon frequency, as known from the literature, we show that the BS mode remains unaffected. Furthermore, it has a characteristic polarization dependence and, unlike the Higgs mode, generates a current in perpendicular direction to the applied field. We find that the Bardasis-Schrieffer excitations contribute a sizable signal to the third harmonic generated current, which is clearly distinguishable from the charge density fluctuations due to Cooper pair breaking effects and can be straightforwardly detected in experiment.

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Section: Effective Actionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Signatures of Bardasis-Schrieffer mode excitation in third-harmonic generated currents

Müller

Eremin

2021

Phys. Rev. B

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“…Presence of a nematic order that spontaneously breaks rotation symmetry in YBCO has been evidenced by Nernst effect measurement below T * ( 50 ). Theoretical investigations indicate that the nematic interaction has a strong impact on the short-time dynamics of unconventional superconductors ( 51 ). Moreover, recent terahertz Kerr measurements have also identified a clear nematic order contribution in iron-based superconductors ( 52 ), while Raman spectroscopy has observed nematic fluctuations in various hole-doped cuprates up to T * ( 53 ).…”

Section: Discussionmentioning

confidence: 99%

Dynamical interplay between superconductivity and pseudogap in cuprates as revealed by terahertz third-harmonic generation spectroscopy

Yuan,

Shi,

Yue

et al. 2024

Sci. Adv.

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We report on nonlinear terahertz third-harmonic generation (THG) measurements on YBa 2 Cu 3 O 6+ x thin films. Different from conventional superconductors, the THG signal starts to appear in the normal state, which is consistent with the crossover temperature T * of pseudogap over broad doping levels. Upon lowering the temperature, the THG signal shows an anomaly just below T c in the optimally doped sample. Notably, we observe a beat pattern directly in the measured real-time waveform of the THG signal. We elaborate that the Higgs mode, which develops below T c , couples to the mode already developed below T * , resulting in an energy level splitting. However, this coupling effect is not evident in underdoped samples. We explore different potential explanations for the observed phenomena. Our research offers valuable insight into the interplay between superconductivity and pseudogap.

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“…3). Also noticeable is a reduction of the linewidth of both branches (better seen in an energy cut along a fixed wave vector, as in fig 4. This means that the sandwich geometry produces longer-lived hybrid modes than the simpler bilayer geometry, which could be important for applications.…”

Section: Gr -Fese -Grmentioning

confidence: 91%

Enhancing the hybridization of plasmons in graphene with 2D superconductor collective modes

Costa,

Peres

2021

Preprint

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We explore ways in which the close proximity between graphene sheets and monolayers of 2D superconductors can lead to hybridization between their collective excitations. We consider heterostructures formed by combinations of graphene sheets and 2D superconductor monolayers. The broad range of energies in which the graphene plasmon can exist, together with its tunability, makes such heterostrucutres promising platforms for probing the many-body physics of superconductors. We show that the hybridization between the graphene plasmon and the Bardasis-Schrieffer mode of a 2D superconductor results in clear signatures on the near-field reflection coefficient of the heterostructure, which in principle can be observed in scanning near-field microscopy experiments.

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Interplay between nematicity and Bardasis-Schrieffer modes in the short-time dynamics of unconventional superconductors

Cited by 8 publications

References 65 publications

Signatures of Bardasis-Schrieffer mode excitation in third-harmonic generated currents

Signatures of Bardasis-Schrieffer mode excitation in third-harmonic generated currents

Dynamical interplay between superconductivity and pseudogap in cuprates as revealed by terahertz third-harmonic generation spectroscopy

Enhancing the hybridization of plasmons in graphene with 2D superconductor collective modes

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