Wang, Q. Y. et al. Interface-induced high-temperature superconductivity in single unit-cell FeSe films on SrTiO3. Chin. Phys. Lett. 29, 037402 (2012).
Lee, J. J. et al. Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3. Nature 515, 245â248 (2014).
Peng, R. et al. Tuning the band structure and superconductivity in single-layer FeSe by interface engineering. Nat. Commun. 5, 5044 (2014).
Liu, X. et al. Dichotomy of the electronic structure and superconductivity between single-layer and double-layer FeSe/SrTiO3 films. Nat. Commun. 5, 5047 (2014).
Zhang, C. et al. Ubiquitous strong electron-phonon coupling at the interface of FeSe/SrTiO3. Nat. Commun. 8, 14468 (2017).
Shi, R. et al. Atomic-scale observation of localized phonons at FeSe/SrTiO3 interface. Nat. Commun. 15, 3418 (2024).
Liu, D. et al. Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor. Nat. Commun. 3, 931 (2012).
Zhang, W. et al. Interface charge doping effects on superconductivity of single-unit-cell FeSe films on SrTiO3 substrates. Phys. Rev. B 89, 060506(R) (2014).
Zhang, H. et al. Origin of charge transfer and enhanced electron-phonon coupling in single unit-cell FeSe films on SrTiO3. Nat. Commun. 8, 214 (2017).
Miyata, Y., Nakayama, K., Sugawara, K., Sato, T. & Takahashi, T. High-temperature superconductivity in potassium-coated multilayer FeSe thin films. Nat. Mater. 14, 775â779 (2015).
Lei, B. et al. Evolution of high-temperature superconductivity from a low-Tc phase tuned by carrier concentration in FeSe thin flakes. Phys. Rev. Lett. 116, 077002 (2016).
Wen, C. H. P. et al. Anomalous correlation effects and unique phase diagram of electron-doped FeSe revealed by photoemission spectroscopy. Nat. Commun. 7, 10840 (2016).
Zhang, W. H. et al. Direct observation of high-temperature superconductivity in one-unit-cell FeSe films. Chin. Phys. Lett. 31, 017401 (2014).
Ge, J. F. et al. Superconductivity above 100 K in single-layer FeSe films on doped SrTiO3. Nat. Mater. 14, 285â289 (2015).
He, S. et al. Phase diagram and electronic indication of high-temperature superconductivity at 65âK in single-layer FeSe films. Nat. Mater. 12, 605â610 (2013).
Tan, S. et al. Interface-induced superconductivity and strain-dependent spin density waves in FeSe/SrTiO3 thin films. Nat. Mater. 12, 634â640 (2013).
Xu, Y. et al. Spectroscopic evidence of superconductivity pairing at 83 K in single-layer FeSe/SrTiO3 films. Nat. Commun. 12, 2840 (2021).
Fan, Q. et al. Plain s-wave superconductivity in single-layer FeSe on SrTiO3 probed by scanning tunnelling microscopy. Nat. Phys. 11, 946â952 (2015).
Song, Q. et al. Evidence of cooperative effect on the enhanced superconducting transition temperature at the FeSe/SrTiO3 interface. Nat. Commun. 10, 758 (2019).
Liu, C. et al. High-order replica bands in monolayer FeSe/SrTiO3 revealed by polarization-dependent photoemission spectroscopy. Nat. Commun. 12, 4573 (2021).
Faeth, B. D. et al. Interfacial electron-phonon coupling constants extracted from intrinsic replica bands in monolayer FeSe/SrTiO3. Phys. Rev. Lett. 127, 016803 (2021).
Fuchs, R. & Kliewer, K. L. Optical modes of vibration in an ionic crystal slab. Phys. Rev. 140, A2076 (1965).
Zhang, S. et al. Role of SrTiO3 phonon penetrating into thin FeSe films in the enhancement of superconductivity. Phys. Rev. B 94, (2016).
Zhang, S. et al. Enhanced superconducting state in FeSe/SrTiO3 by a dynamic interfacial polaron mechanism. Phys. Rev. Lett. 122, 066802 (2019).
Li, F. et al. Atomically resolved FeSe/SrTiO3(001) interface structure by scanning transmission electron microscopy. 2D Mater. 3, 024002 (2016).
Sims, H. et al. Intrinsic interfacial van der Waals monolayers and their effect on the high-temperature superconductor FeSe/SrTiO3. Phys. Rev. B 100, 144103 (2019).
Peng, R. et al. Picoscale structural insight into superconductivity of monolayer FeSe/SrTiO3. Sci. Adv. 6, eaay4517 (2020).
Krivanek, O. L. et al. Vibrational spectroscopy in the electron microscope. Nature 514, 209â212 (2014).
Venkatraman, K., Levin, B. D. A., March, K., Rez, P. & Crozier, P. A. Vibrational spectroscopy at atomic resolution with electron impact scattering. Nat. Phys. 15, 1237â1241 (2019).
Hage, F. S., Radtke, G., Kepaptsoglou, D. M., Lazzeri, M. & Ramasse, Q. M. Single-atom vibrational spectroscopy in the scanning transmission electron microscope. Science 367, 1124â1127 (2020).
Xu, M. et al. Single-atom vibrational spectroscopy with chemical-bonding sensitivity. Nat. Mater. 22, 612â618 (2023).
Yan, X. et al. Single-defect phonons imaged by electron microscopy. Nature 589, 65â69 (2021).
Yan, X. et al. Real-space visualization of frequency-dependent anisotropy of atomic vibrations. Preprint at https://arxiv.org/abs/2312.01694 (2023).
Erdman, N. et al. The structure and chemistry of the TiO2-rich surface of SrTiO3 (001). Nature 419, 55â58 (2002).
Kubo, T. & Nozoye, H. Surface structure of SrTiO3(100). Surf. Sci. 542, 177â191 (2003).
Andersen, T. K., Fong, D. D. & Marks, L. D. Paulingâs rules for oxide surfaces. Surf. Sci. Rep. 73, 213â232 (2018).
Zou, K. et al. Role of double TiO2 layers at the interface of FeSe/SrTiO3 superconductors. Phys. Rev. B 93, 180506 (2016).
Pedersen, A. K. et al. Interfacial superconductivity in FeSe ultrathin films on SrTiO3 probed by in situ independently driven four-point-probe measurements. Phys. Rev. Lett. 124, 227002 (2020).
Hage, F. S., Kepaptsoglou, D. M., Ramasse, Q. M. & Allen, L. J. Phonon spectroscopy at atomic resolution. Phys. Rev. Lett. 122, 016103 (2019).
Yang, H. et al. Inelastic electron scattering at large angles: the phonon polariton contribution. Preprint at https://arxiv.org/abs/2401.04719 (2024).
Nicholls, R. J. et al. Theory of momentum-resolved phonon spectroscopy in the electron microscope. Phys. Rev. B 99, 094105 (2019).
Zeiger, P. M. & Rusz, J. Efficient and versatile model for vibrational STEM-EELS. Phys. Rev. Lett. 124, 025501 (2020).
Rademaker, L., Wang, Y., Berlijn, T. & Johnston, S. Enhanced superconductivity due to forward scattering in FeSe thin films on SrTiO3 substrates. New J. Phys. 18, 022001 (2016).
Rademaker, L., Alvarez-Suchini, G., Nakatsukasa, K., Wang, Y. & Johnston, S. Enhanced superconductivity in FeSe/SrTiO3 from the combination of forward scattering phonons and spin fluctuations. Phys. Rev. B 103, 144504 (2021).
Zhao, W. et al. Direct imaging of electron transfer and its influence on superconducting pairing at FeSe/SrTiO3 interface. Sci. Adv. 4, eaao2682 (2018).
Lee, D. H. What makes the Tc of FeSe/SrTiO3 so high? Chin. Phys. B 24, 117405 (2015).
Kang, B. L. et al. Preformed Cooper pairs in layered FeSe-based superconductors. Phys. Rev. Lett. 125, 97003 (2020).
Faeth, B. D. et al. Incoherent Cooper pairing and pseudogap behavior in single-layer FeSe/SrTiO3. Phys. Rev. X 11, 021054 (2021).
Ide, K., Tanaka, T., Pedersen, A., Ichinokura, S. & Hirahara, T. Temperature dependence of the superconducting gap of single-layer FeSe/SrTiO3: direct comparison between transport and spectroscopic measurements. Phys. Rev. Mater. 6, 124801 (2022).
Guan, J. et al. Superconducting transition of FeSe/SrTiO3 induced by adsorption of semiconducting organic molecules. Phys. Rev. B 95, 205405 (2017).
Qi, R. et al. Four-dimensional vibrational spectroscopy for nanoscale mapping of phonon dispersion in BN nanotubes. Nat. Commun. 12, 1179 (2021).
Hoglund, E. R. et al. Emergent interface vibrational structure of oxide superlattices. Nature 601, 556â561 (2022).
Batson, P. E. & Lagos, M. J. Interpretation of meV resolution phonon EELS data. Microsc. Microanal. 24, 412â413 (2018).
Blochl, P. E. Projector augmented-+rave method. Phys. Rev. B 50, 24 (1994).
Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758â1775 (1999).
Perdew, J. P. & Zunger, A. Self-interaction correction to density-functional approximations for many-electron systems. Phys. Rev. B 23, 5048â5079 (1981).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169â11186 (1996).
Methfessel, M. & Paxton, A. T. High-precision sampling for Brillouin-zone integration in metals. Phys. Rev. B 40, 3616â3621 (1989).
Baroni, S., De Gironcoli, S., Corso, A. D. & Giannozzi, P. Phonons and related crystal properties from density-functional perturbation theory. Rev. Mod. Phys. 73, 515â562 (2001).
Gonze, X. First-principles responses of solids to atomic displacements and homogeneous electric fields: Implementation of a conjugate-gradient algorithm. Phys. Rev. B 55, 10337â10354 (1997).
Gonze, X. & Lee, C. Dynamical matrices, Born effective charges, dielectric permittivity tensors, and interatomic force constants from density-functional perturbation theory. Phys. Rev. B 55, 10355â10368 (1997).
Anisimov, V. I., Zaanen, J. & Andersen, O. K. Band theory and Mott insulators: Hubbard U instead of Stoner I. Phys. Rev. B 44, 943â954 (1991).
Giannozzi, P. et al. QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials. J. Phys. Condens. Matter 21, 395502 (2009).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865â3868 (1996).
Mitchell, R. H., Chakhmouradian, A. R. & Woodward, P. M. Crystal chemistry of perovskite-type compounds in the tausonite-loparite series, (Sr1â2xNaxLax)TiO3. Phys. Chem. Miner. 27, 583â589 (2000).
Zeiger, P. M. & Rusz, J. Frequency-resolved frozen phonon multislice method and its application to vibrational electron energy loss spectroscopy using parallel illumination. Phys. Rev. B 104, 104301 (2021).
Chen, X., Kim, D. S. & LeBeau, J. M. A comparison of molecular dynamics potentials used to account for thermal diffuse scattering in multislice simulations. Ultramicroscopy 244, 113644 (2023).
Barthel, J. Dr. Probe: a software for high-resolution STEM image simulation. Ultramicroscopy 193, 1â11 (2018).
