Evolution of spin excitations from bulk to monolayer FeSe
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 25, 2021
- Source ID
- 10.1038/s41467-021-23317-3
Entities
People
- Abhishek Nag
- Andrew C. Walters
- Donglai Feng
- Giacomo Ghiringhelli
- Jiemin Li
- Jonathan Pelliciari
- Jun Zhao
- Ke-Jin Zhou
- Matteo Rossi
- Mirian García‐Fernández
- Qi Song
- Qisi Wang
- Riccardo Arpaia
- Riccardo Comin
- Rui Peng
- Seher Karakuzu
- Steven Johnston
- Thomas A. Maier
- Tianlun Yu
- Xiaoyang Chen
Organizations
- Fondazione Cariplo
- National Natural Science Foundation of China
- Office of Naval Research
- Office of Science
- Swedish Research Council
- Swiss National Science Foundation
- United States Air Force