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Main Authors: Taniguchi, Yuto, Kato, Ryo, Amano, Tatsuya, Itoh, Hirotake, Kawakam, Yohei, Nakamura, Yuto, Kishida, Hideo, Bernhard, Christian, Demsar, Jure, Sasaki, Takahiko, Nishizaki, Terukazu, Yonemitsu, Kenji, Iwai, Shinichiro
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.14238
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author Taniguchi, Yuto
Kato, Ryo
Amano, Tatsuya
Itoh, Hirotake
Kawakam, Yohei
Nakamura, Yuto
Kishida, Hideo
Bernhard, Christian
Demsar, Jure
Sasaki, Takahiko
Nishizaki, Terukazu
Yonemitsu, Kenji
Iwai, Shinichiro
author_facet Taniguchi, Yuto
Kato, Ryo
Amano, Tatsuya
Itoh, Hirotake
Kawakam, Yohei
Nakamura, Yuto
Kishida, Hideo
Bernhard, Christian
Demsar, Jure
Sasaki, Takahiko
Nishizaki, Terukazu
Yonemitsu, Kenji
Iwai, Shinichiro
contents Understanding how quasiparticles are generated following a rapid quench of superconductivity in high-Tc cuprates is a key unresolved problem in nonequilibrium superconductivity. Here we resolve these processes in optimally doped YBCO [YBa2Cu3Oy(y=6.94, Tc=92 K)] using broadband (0.16 -4.1 eV, ca. 100 fs) and nearly single-cycle (6 fs) transient reflectivity spectroscopy. We show that within a few femtosecond, enhanced electron-electron Umklapp scattering dominates, signaling a transient modulation of long-range Coulomb interactions on the eV scale. This regime is followed by a rapid suppression of the scattering rate of the mid-infrared absorption associated with carriers dressed by spin fluctuations. We attribute this observation to an ultrafast decoupling of quasiparticles from the spin-fluctuation background, occurring on a 90 fs timescale set by the inverse optical gap. These findings reveal the correlated many-body dynamics underlying quasiparticle generation in cuprates and provide further clues for unconventional pairing mechanism.
format Preprint
id arxiv_https___arxiv_org_abs_2605_14238
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Ultrafast decoupling of quasiparticles and spin fluctuations in superconducting cuprates
Taniguchi, Yuto
Kato, Ryo
Amano, Tatsuya
Itoh, Hirotake
Kawakam, Yohei
Nakamura, Yuto
Kishida, Hideo
Bernhard, Christian
Demsar, Jure
Sasaki, Takahiko
Nishizaki, Terukazu
Yonemitsu, Kenji
Iwai, Shinichiro
Strongly Correlated Electrons
Understanding how quasiparticles are generated following a rapid quench of superconductivity in high-Tc cuprates is a key unresolved problem in nonequilibrium superconductivity. Here we resolve these processes in optimally doped YBCO [YBa2Cu3Oy(y=6.94, Tc=92 K)] using broadband (0.16 -4.1 eV, ca. 100 fs) and nearly single-cycle (6 fs) transient reflectivity spectroscopy. We show that within a few femtosecond, enhanced electron-electron Umklapp scattering dominates, signaling a transient modulation of long-range Coulomb interactions on the eV scale. This regime is followed by a rapid suppression of the scattering rate of the mid-infrared absorption associated with carriers dressed by spin fluctuations. We attribute this observation to an ultrafast decoupling of quasiparticles from the spin-fluctuation background, occurring on a 90 fs timescale set by the inverse optical gap. These findings reveal the correlated many-body dynamics underlying quasiparticle generation in cuprates and provide further clues for unconventional pairing mechanism.
title Ultrafast decoupling of quasiparticles and spin fluctuations in superconducting cuprates
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2605.14238