Electronic Quasiparticle Renormalization on the Spin Wave Energy Scale

Abstract

High-resolution photoemission data of the (110) iron surface reveal the existence of well-defined metallic surface resonances in good correspondence to band calculations. Close to the Fermi level, their dispersion and momentum broadening display anomalies characteristic of quasiparticle renormalization due to coupling to bosonic excitations. Its energy scale exceeds that of phonons by far, and is in striking coincidence with that of the spin wave spectrum in iron. The self-energy behavior thus gives spectroscopic evidence of a quasiparticle mass enhancement due to electron-magnon coupling.

Effects of spin-dependent quasiparticle renormalization in Fe, Co, and Ni photoemission spectra:An experimental and theoretical study

“…This energy range is quite different from that discussed in recent high-resolution ARPES studies on Fe or Ni. 28,30,71 There, the very low BE range E B 300 meV has been treated, in which a renormalization of the charge carrier dynamics by a coupling to phonon or magnetic excitations is important. All the observed peaks in Figs.…”

“…27,28 It has been shown that very close to the Fermi energy mass renormalizations are even higher, reaching values up to 3.6. [28][29][30] Moreover a strong broadening of the ARPES peaks in Fe has been observed amounting to about 60% of the BE. 27 Most recently, we have published a detailed comparison of SARPES measurements and DMFT/3BS calculations on Fe indicating that the present state-of-the art many-body calculations still underestimate correlation effects.…”

Kinks in theσBand of Graphene Induced by Electron-Phonon Coupling

“…Such kinks are primarily caused by electron-boson interactions and many cases of electron-phonon [1][2][3] or electron-magnon [4] induced kinks have been reported. In the cuprate hightemperature superconductors, strong kinks have been found near the Fermi energy [5,6], and their origin as well as their significance for the mechanism for hightemperature superconductivity have given reason to some debate [7].…”

Photoemission as a Probe of the Collective Excitations in Condensed Matter Systems

“…[50] In studies of the Fe(001) surface Schafer et al identified a mass renormalization up to a binding energy of 120 meV. The latter energy was too large to be associated with phonons (Debye energy, θ D ∼ 39 meV) and thus the authors identified the self-energy corrections with scattering from spin excitations.…”

“…Such effects have been found in photoemission studies of gadolinium [48] [49] and of iron. [50] The spin dependent electronic structure of these materials has been studied with spin-resolved photoemission. [51] However there has only been one such study with sufficiently high energy resolution to examine in detail the spin resolved self-energy effects.…”