Detection of bosonic mode as a signature of magnetic excitation in one unit cell FeSe on SrTiO3

Abstract

We report an in situ scanning tunneling spectroscopy study of one-unit-cell (1-UC) FeSe film on SrTiO3(001) (STO) substrate. In quasiparticle density of states, bosonic excitation mode characterized by the "dip-hump" structure is detected outside the larger superconducting gap with energy comparable with phonon and spin resonance modes in heavily electron-doped iron selenides. Statistically, the excitation mode, which is intimately correlated with superconductivity, shows an anticorrelation with pairing strength and yields an energy scale upper-bounded by twice the superconducting gap coinciding with the characteristics of magnetic resonance in cuprates and iron-based superconductors. The local response of tunneling spectra to magnetically different Se defects all exhibits the induced in-gap quasiparticle bound states, indicating an unconventional sign-reversing pairing. These results support the magnetic nature of the excitation mode and possibly reveal a signature of electron-magnetic-excitation coupling in high-temperature superconductivity of 1-UC FeSe/STO.

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• Discovery of a pair density wave state in a monolayer high-Tc iron-based superconductor
• Observation of superconducting collective modes from competing pairing instabilities in single-layer NbSe${}_2$
• Heterostructural one-unit-cell FeSe/SrTiO3: from high-temperature superconductivity to topological states
• Tuning stoichiometry and its impact on superconductivity of monolayer and multilayer FeSe on SrTiO3
• Emergent vortex Majorana zero mode in iron-based superconductors
• Multichannel superconductivity of monolayer FeSe on SrTiO${}_3$: Interplay of spin fluctuations and electron-phonon interaction
• Evidence of a distinct collective mode in Kagome superconductors
• Direct probing of a large spin-orbit coupling in the FeSe superconducting monolayer on STO: Evidence for nontrivial topological states
• The study of intrinsic defect state of FeSe with scanning tunneling microscopy
• Checkerboard order state in superconducting FeSe/SrTiO3(001) monolayer
• Orbital-Selective High-Temperature Cooper Pairing Developed in the Two-Dimensional Limit
• Superconductivity of the FeSe/SrTiO3 Interface in the View of BCS-BEC Crossover
• Direct evidence of a charge depletion region at the interface of Van der Waals monolayers and dielectric oxides: The case of superconducting FeSe/STO
• Lateral quantum confinement effect on monolayer high-Tc superconductors
• Capping layer influence and isotropic in-plane upper critical field of the superconductivity at the FeSe/SrTiO3 interface
• Dynamical Coulomb Blockade as a Signature of the Sign-Reversing Cooper Pairing Potential
• Temperature evolution of the Fermi surface of the FeSe monolayer on SrTiO${}_3$
• Spectroscopic evidence of disorder-induced quantum phase transitions in monolayer Fe(Te,Se) superconductor