Separated Electron–Phonon and Phonon–Phonon Scatterings Across Interface in Thin Film LaCoO₃/SrTiO₃

Abstract

Electron–phonon coupling (EPC) and phonon–phonon scattering (PPS) are at the core of the microscopic physics mechanisms of vast quantum materials. However, to date, there are rarely reports that these two processes can be spatially separated, although they are usually temporally detached with different characteristic lifetimes. Here, by employing ultrafast spectroscopy to investigate the photo‐carrier ultrafast dynamics in a LaCoO3 thin film on a (100) SrTiO3 substrate, intriguing evidence is found that the two interactions are indeed spatially separated. The EPC mainly occurs in the thin film, whereas PPS is largely in the substrate, especially at the several atomic layers near the interface. Across‐interface penetration and decay of optical phonons into acoustic phonons thus naturally occur. An EPC strength λEg = 0.30 is also obtained and an acoustic phonon mode at 45.3 GHz is observed. The finding lays out a cornerstone for future quantum nano device designs.

Photodoping-Modified Charge Density Wave Phase Transition in WS2/1T-TaS2 Heterostructure

“…[19] Optical pump-probe spectroscopy is a unique tool for studying the formation of diverse CDW orders with temperature, which offers valuable insights into the nonequilibrium carrier dynamics of correlated materials. [24,25] In this work, we employ time-resolved spectroscopy to investigate the modification of the CDW phase transition in WS2/1T-TaS2 HS. By directly comparing the phase transition process between pristine 1T-TaS2 and corresponding WS2/1T-TaS2 HS, we distinguish the distinctive roles of photo-induced charge transfer doping in influencing the CDW phase.…”