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Evolution of spin excitations from bulk to monolayer FeSe

DOI: 10.1038/s41467-021-23317-3 DOI Help

Authors: Jonathan Pelliciari (Massachusetts Institute of Technology; NSLS-II) , Seher Karakuzu (Oak Ridge National Laboratory) , Qi Song (Fudan University) , Riccardo Arpaia (Politecnico di Milano; Chalmers University of Technology) , Abhishek Nag (Diamond Light Source) , Matteo Rossi (Politecnico di Milano) , Jiemin Li (Diamond Light Source) , Tianlun Yu (Fudan University) , Xiaoyang Chen (Fudan University) , Rui Peng (Fudan University) , Mirian Garcia-Fernandez (Diamond Light Source) , Andrew C. Walters (Diamond Light Source) , Qisi Wang (Fudan University) , Jun Zhao (Fudan University) , Giacomo Ghiringhelli (Politecnico di Milano) , Donglai Feng (Fudan University) , Thomas A. Maier (Oak Ridge National Laboratory) , Ke-Jin Zhou (Diamond Light Source) , Steven Johnston (The University of Tennessee) , Riccardo Comin (Massachusetts Institute of Technology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 12

State: Published (Approved)
Published: May 2021
Diamond Proposal Number(s): 18883

Open Access Open Access

Abstract: In ultrathin films of FeSe grown on SrTiO3 (FeSe/STO), the superconducting transition temperature Tc is increased by almost an order of magnitude, raising questions on the pairing mechanism. As in other superconductors, antiferromagnetic spin fluctuations have been proposed to mediate SC making it essential to study the evolution of the spin dynamics of FeSe from the bulk to the ultrathin limit. Here, we investigate the spin excitations in bulk and monolayer FeSe/STO using resonant inelastic x-ray scattering (RIXS) and quantum Monte Carlo (QMC) calculations. Despite the absence of long-range magnetic order, bulk FeSe displays dispersive magnetic excitations reminiscent of other Fe-pnictides. Conversely, the spin excitations in FeSe/STO are gapped, dispersionless, and significantly hardened relative to its bulk counterpart. By comparing our RIXS results with simulations of a bilayer Hubbard model, we connect the evolution of the spin excitations to the Fermiology of the two systems revealing a remarkable reconfiguration of spin excitations in FeSe/STO, essential to understand the role of spin fluctuations in the pairing mechanism.

Journal Keywords: Electronic properties and materials; Superconducting properties and materials; Surfaces, interfaces and thin films

Subject Areas: Materials, Physics

Instruments: I21-Resonant Inelastic X-ray Scattering (RIXS)

Added On: 31/05/2021 08:47


Discipline Tags:

Surfaces Superconductors Quantum Materials Hard condensed matter - electronic properties Physics Materials Science interfaces and thin films

Technical Tags:

Scattering Resonant Inelastic X-ray Scattering (RIXS)