Monolayer FeSe on SrTiO${}_3$

Abstract

Epitaxial engineering of solid-state heterointerfaces is a leading avenue to realizing enhanced or novel electronic states of matter. As a recent example, bulk FeSe is an unconventional superconductor with a modest transition temperature ($T_c$) of 9 K. When a single atomic layer of FeSe is grown on SrTiO${}_3$, however, its $T_c$ can skyrocket by an order of magnitude to 65 K or 109 K. Since this discovery in 2012, efforts to reproduce, understand, and extend these findings continue to draw both excitement and scrutiny. In this review, we first present a critical survey of experimental measurements performed using a wide range of techniques. We then turn to the open question of microscopic mechanisms of superconductivity. We examine contrasting indications for both phononic (conventional) and magnetic/orbital (unconventional) means of electron pairing, and speculations about whether they could work cooperatively to boost $T_c$ in a monolayer of FeSe.

27 pages, 14 figures

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Cited by in corpus (26)

• Ironing out the details of unconventional superconductivity
• Unconventional Superconductivity
• Nematicity, magnetism and superconductivity in FeSe
• The key ingredients of the electronic structure of FeSe
• The 2021 Quantum Materials Roadmap
• Exotic Superconducting States in FeSe-based Materials
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Resilient nodeless $d$-wave superconductivity in monolayer FeSe
• Evidence for d-wave superconductivity in single layer FeSe/SrTiO3 probed by quasiparticle scattering off step edges
• Lattice Dynamics of Ultrathin FeSe Films on SrTiO3
• Quantum geometric effect on Fulde-Ferrell-Larkin-Ovchinnikov superconductivity
• Eliashberg theory for spin-fluctuations mediated superconductivity -- Application to bulk and monolayer FeSe
• Intertwined spin-orbital coupled orders in the iron-based superconductors
• Superconductivity enhanced by pair fluctuations between wide and narrow bands
• Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates
• Identification of a Large Amount of Excess Fe in Superconducting Single-Layer FeSe/SrTiO3 Films
• Stoichiometry and defect superstructures in epitaxial FeSe films on SrTiO3
• Checkerboard order state in superconducting FeSe/SrTiO3(001) monolayer
• Role of electric fields on enhanced electron correlation in surface-doped FeSe
• $\text{Ab initio}$ derivation of effective Hamiltonian for La${}_2$CuO${}_4$/La${}_{1.55}$Sr${}_{0.45}$CuO${}_4$ heterostructure
• Orbital-Selective High-Temperature Cooper Pairing Developed in the Two-Dimensional Limit
• Strong enhancement of magnetic order from bulk to stretched monolayer FeSe as Hund's metals
• Unique properties of the optical activity in noncentrosymmetric superconductors: sum rule, missing area, and relation with the superconducting Edelstein effect
• LaO as a candidate substrate for realizing superconductivity in FeSe epitaxial film
• Higher-Order Topology in Monolayer FeSe
• Anisotropic superconductivity induced at a hybrid superconducting-semiconducting interface