High-Energy Kink Observed in the Electron Dispersion of High-Temperature Cuprate Superconductors

Abstract

Photoemission studies show the presence of a high-energy anomaly in the observed band dispersion for two families of cuprate superconductors, Bi2Sr2CaCu2O8+delta and La 2-x BaxCuO4. The anomaly, which occurs at a binding energy of approximately 340 meV, is found to be anisotropic and relatively weakly doping dependent. Scattering from short range or nearest neighbor spin excitations is found to supply an adequate description of the observed phenomena.

High-energy anomaly in Nd2−xCexCuOSchmitt1, Moritz2, Johnston3 et al. 2011Phys. Rev. B9560View full textAdd to dashboardCite

“…9 These findings led to several scenarios for the emergence of the HEA based on interaction with high energy bosonic degrees of freedom, 12,13,20-23 chiefly antiferromagnetic spin fluctuations or paramagnons, 12,[21][22][23] adding to the growing list of scenarios for the emergence of this feature in the band dispersion. [8][9][10][11]14,[24][25][26][27][28][29] However, the vertical drop-off at higher energies, and apparent "back-bending" in some data, calls into question this large bandwidth, quasiparticle scenario and the justification for LDA fits or even Lorentzian momentum distribution curve (MDC) fits in the energy window below the HEA energy scale, also highlighted by the results from laser-based ARPES.…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] ARPES reveals dispersing quasiparticles with sharp spectral features close to E F that give way to an almost vertical dispersion around ∼ 0.3 eV for the hole(h)-doped HTSCs [6][7][8][9][10][11][12][13][14]16,18 , and ∼ 0.5 eV for the electron(e)-doped HTSCs. 6,15,[17][18][19] This vertical dispersion or "waterfall" eventually merges with the incoherent valence bands at higher binding-energies.…”

“…[6][7][8][9][10][11][12][13][14]16,18 In some of these early studies, the HEA was tied to a presumed underlying dispersion through a sizable renormalization in the quasiparticle bare band.…”

Isotropic Kink and Quasiparticle Excitations in the Three-Dimensional Perovskite ManganiteLa0.6Sr0.4MnO3Horiba1, Kitamura2, Yoshimatsu3 et al. 2016Phys. Rev. Lett.19290View full textAdd to dashboardCite

“…In order to determine the characteristic energy scale for the observed kink structure, we have experimentally determined the real part [ReΣ(ω)] and the imaginary part [ImΣ(ω)] of the self-energy as functions of binding energy ω from the width ∆k and the peak positions k m of the MDCs in the ARPES spectra. If we assume that the bare band dispersion near E F is linear, the ReΣ(ω) and ImΣ(ω) can be expressed by the following equations [25]:…”

Insights on the cuprate high energy anomaly observed in ARPES

“…High resolution experiments, at binding energies up to 1 eV and higher, made possible by these advances, have revealed the presence of a "waterfall"-like structure with a characteristic kink at intermediate binding energies -the high energy anomaly (HEA) -in the dispersion of high T c superconductors. [2][3][4][5][6][7][8][9][10][11][12] Found universally in hole-doped compounds, the characteristic HEA energy scale is ∼ 300 meV with a similar dispersion anomaly observed in the half-filled parent insulators. [13] In contrast to earlier low energy studies focusing on dispersion kinks under ∼ 100 meV, [14] interpreted as signatures of coupling to low energy bosonic modes, [15][16][17] the extrapolated band bottom has a value larger than that obtained from band structure calculations [2,3] and the energy scale associated with the anomaly would tend to rule-out coupling to similar bosonic modes as the origin of the HEA.…”