Evidence for phonon-like charge and spin fluctuations from an analysis of angle-resolved photoemission spectra of La2−xSrxCuO

Abstract

In high temperature superconductors we provide evidence of spin and mixed phonon-charge collective modes as mediators of the effective electron-electron interaction and suggestive of a charge and spin density wave instability competing with superconductivity. Indeed, we show that the so-called kinks and waterfalls observed in angle-resolved photoemission spectra of La 2−x Sr x CuO 4 , a prototypical high-T c superconducting cuprate, are due to the coupling of quasiparticles with two distinct nearly critical collective modes with finite characteristic wave vectors, typical of charge and spin fluctuations. The simultaneous presence of these two modes reconciles the long standing dichotomy whether kinks are due to phonons or spin waves.

Phase diagrams of voltage-gated oxide interfaces with strong Rashba coupling

“…The fact that (nearly) neu-tral large-scale density fluctuations might occur in these systems is the key point allowing to escape the Coulombic frustration usually invoked to produce z = 1 critical fluctuations. [62][63][64] Of course, the possibility is also open that Coulombic forces frustrate the phase separation giving rise to charge-density waves (or even anharmonic stripes) similar to what has been proposed in high T c cuprates, 50,51,60,[65][66][67][68] likely yielding a dynamical critical index z = 2.…”

Anomalous High-Energy Waterfall-Like Electronic Structure in 5 d Transition Metal Oxide Sr2IrO4 with a Strong Spin-Orbit Coupling

“…The revelation of the high energy waterfall-like bands in Sr 2 IrO 4 provides another system that can be used to compare and contrast with the cuprates in order to understand the origin of the high energy anomaly. In the cuprate superconductors, the high energy anomalous band has attracted extensive experimental 26 27 28 29 30 31 32 33 34 35 and theoretical interest 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 although there has been no consensus reached on its origin. The prime candidate for the anomalous high energy behavior can be simply an intrinsic property of a strong electron correlation system or Mott physics 30 36 38 44 45 46 48 49 51 52 .…”

“…The prime candidate for the anomalous high energy behavior can be simply an intrinsic property of a strong electron correlation system or Mott physics 30 36 38 44 45 46 48 49 51 52 . The second possibility is due to quasiparticle scattering with some electronic or bosonic excitations, such as phonons 28 , plasmons 39 , paramagnons 29 40 42 49 , and other spin and charge excitations 53 . It can also be due to other novel effects such as the spin-charge separation 27 , spin polarons 37 , photoemission matrix element effect 32 , charge modulations 41 , quantum critical fluctuation 43 , in-gap band-tails 47 and so on.…”

The Ancient Romans’ Route to Charge Density Waves in Cuprates

“…Along the years, it was possible to account for the occurrence of shadow bands [30][31][32][33][34][35][36][37], to describe the peculiarities of the electron spectrum known as kinks and waterfalls [38][39][40], and the effect of a bilayer splitting [41] in systems with two CuO 2 planes per unit cell.…”

“…It must be pointed out that angle resolved photoemission spectra of cuprates (as well as many other spectral porperties) are also affected by nearly antiferromagnetic spin density fluctuations [30,40], with their characteristic wave vector q AFM c ≈ (π, π). The specificity of charge density waves is that their characteristic wave vector q c is along the CuO bonds, in the (1, 0) and (0, 1) directions of the Brillouin zone, and contribute with features that cannot be associated to scattering processes involving a mediator with a larger characteristic wave vector, q AFM c , pointing along the diagonals of the Brillouin zone.…”