Low-energy electron-mode couplings in the surface bands of Sr2RuO4 revealed by laser-based angle-resolved photoemission spectroscopy

We use angle-resolved photoemission spectroscopy with a 7-eV laser, which is capable of ultrahigh energy and momentum resolutions, and investigate bosonic mode couplings in the surface bands of Sr2RuO4. Significantly, our measurements reveal pronounced kink structures at very low binding energies (~...

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Bibliographic Details
Published in:Physical review. B 2019-02, Vol.99 (8), p.081108(R)
Main Authors: Akebi, Shuntaro, Kondo, Takeshi, Nakayama, Mitsuhiro, Kuroda, Kenta, Kunisada, So, Taniguchi, Haruka, Maeno, Yoshiteru, Shin, Shik
Format: Article
Language:English
Subjects:
Banded structure
Couplings
Electron spin
Ferromagnetism
Laser applications
Neutron scattering
Neutrons
Photoelectric emission
Photoelectron spectroscopy
Spectrum analysis
Strontium ruthenium oxide
Variations
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Summary:We use angle-resolved photoemission spectroscopy with a 7-eV laser, which is capable of ultrahigh energy and momentum resolutions, and investigate bosonic mode couplings in the surface bands of Sr2RuO4. Significantly, our measurements reveal pronounced kink structures at very low binding energies (~8 and ~15 meV), which have a strong variation in the renormalization strength among multiple bands derived from the Ru4d orbitals. Neutron scattering has observed phonon modes with the lowest energy scale around 15 meV, which thus could be the main source for the ~15-meV kink. In contrast, the significant coupling at the lower energy (~8 meV) is attributed to magnetic excitations, which are reported to be peaked in density of states around 10 meV. The ~8-meV kink is found to be strongest in the two-dimensional 4dxy-derived band, implying its mechanism to be the electron coupling to ferromagnetic spin fluctuations.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.99.081108