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.

arXiv comment27 pages, 14 figures

References in corpus (80)

• Conventional superconductivity at 203 K at high pressures
• Unconventional sign-reversing superconductivity in LaFeAsO_(1-x)F_x
• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Gap symmetry and structure of Fe-based superconductors
• Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure
• Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films
• Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3
• Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films
• Is LaO${}_{1-x}$F${}_x$FeAs an electron-phonon superconductor ?
• Electronic Origin of High Temperature Superconductivity in Single-Layer FeSe Superconductor
• High-temperature interface superconductivity between metallic and insulating cuprates
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Structure determination and coexistence of superconductivity and antiferromagnetic order in (Li0.8Fe0.2)OHFeSe
• Emergence of the nematic electronic state in FeSe
• Effect of magnetic frustration on nematicity and superconductivity in Fe chalcogenides
• Enhancement of superconductivity near a nematic quantum critical point
• Direct observation of high temperature superconductivity in one-unit-cell FeSe films
• Reconstruction of Band Structure Induced by Electronic Nematicity in an FeSe Superconductor
• Strong Interplay between Stripe Spin Fluctuations, Nematicity and Superconductivity in FeSe
• Violation of Anderson's Theorem for Sign-Reversing s-Wave State of Iron-Pnictide Superconductors
• Critical role of substrate in the high temperature superconductivity of single layer FeSe on Nb:BaTiO${}_3$
• Lack of coupling between superconductivity and orthorhombic distortion in stoichiometric single-crystalline FeSe
• Lifting of xz/yz orbital degeneracy at the structural transition in detwinned FeSe
• Nematicity and quantum paramagnetism in FeSe
• Magnetic ground state of FeSe
• Common Electronic Origin of Superconductivity in (Li,Fe)OHFeSe Bulk Superconductor and Single-Layer FeSe/SrTiO3 Films
• d-wave pairing from spin fluctuations in the KxFe{2-y}Se2 superconductors
• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3(110)
• Anomalous correlation effects and unique phase diagram of electron doped FeSe revealed by angle resolved photoemission spectroscopy
• Plain s-wave superconductivity in single-layer FeSe on SrTiO3 probed by scanning tunneling microscopy
• Observation of two distinct $d_{xz}/d_{yz}$ band splittings in FeSe
• Manifestations of nematic degrees of freedom in the magnetic, elastic, and superconducting properties of the iron pnictides
• Antiferroquadrupolar and Ising-Nematic Orders of a Frustrated Bilinear-Biquadratic Heisenberg Model and Implications for the Magnetism of FeSe
• Enhanced superconductivity and evidence for novel pairing in single-layer FeSe on SrTiO3 thin film under large tensile strain
• Change of pairing symmetry in the iron-based superconductor KFe2As2
• Surface electronic structure and isotropic superconducting gap in (Li${}_{0.8}$Fe${}_{0.2}$)OHFeSe
• Preparation of atomically-flat SrTiO3 surfaces using a deionized-water etching and thermal annealing procedure
• The origin of nematic order in FeSe
• Enhanced superconductivity due to forward scattering in FeSe thin films on SrTiO3 substrates
• Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films
• High temperature superconducting FeSe films on SrTiO3 substrates
• Superconducting gap anisotropy in monolayer FeSe thin film
• Symmetry analysis of possible superconducting states in KxFe2Se2 superconductors
• High-temperature superconductivity in single-unit-cell FeSe films on anatase TiO2(001)
• Ultrafast Dynamics Evidence of High Temperature Superconductivity in Single Unit Cell FeSe on SrTiO3
• Origin of the large phonon band-gap in SrTiO3 and the vibrational signatures of ferroelectricity in ATiO3 perovskite: First principles lattice dynamics and inelastic neutron scattering of PbTiO3, BaTiO3 and SrTiO3
• Onset of the Meissner effect at 65 K in FeSe thin film grown on Nb doped SrTiO3 substrate
• What makes the Tc of monolayer FeSe on SrTiO3 so high: a sign-problem-free quantum Monte Carlo study
• Strong $(\pi ,0)$ spin fluctuations in $\beta$-FeSe observed by neutron spectroscopy
• The Role of SrTiO3 Phonon Penetrating into thin FeSe Films in the Enhancement of Superconductivity
• Enhanced superconductivity accompanying a Lifshitz transition in electron-doped FeSe monolayer
• Electron pairing in the presence of incipient bands in iron-based superconductors
• Large electron-phonon interactions from FeSe phonons in a monolayer
• Interface enhanced electron-phonon coupling and high temperature superconductivity in potassium-coated ultra-thin FeSe films on SrTiO3
• Scrutinizing the double superconducting gaps and strong coupling pairing in (Li1-xFexOH)FeSe
• Observation of strong electron pairing on bands without Fermi surfaces in LiFe1-xCoxAs
• Observation of high-Tc superconductivity in rectangular FeSe/STO(110) monolayer
• Revealing the Empty-State Electronic Structure of Single-Unit-Cell FeSe/SrTiO${}_3$
• High Tc via spin fluctuations from incipient bands: application to monolayers and intercalates of FeSe
• Atomically Resolved FeSe/SrTiO3(001) Interface Structure by Scanning Transmission Electron Microscopy
• Superconductivity from orbital nematic fluctuations
• Effects of charge doping and constrained magnetization on the electronic structure of an FeSe monolayer
• Superconductivity in FeSe thin films driven by the interplay between nematic fluctuations and spin-orbit coupling
• Surface electronic structure and evidence of plain s-wave superconductivity in (Li0.8Fe0.2)OHFeSe
• Superconductivity dichotomy in K-coated single and double unit cell FeSe films on SrTiO3
• Oxygen Vacancy Induced Flat Phonon Mode at FeSe /SrTiO3 interface
• The role of double TiO2 layers at the interface of FeSe/SrTiO3 superconductors
• Three-dimensionality and orbital characters of Fermi surface in (Tl,Rb)${}_y$Fe${}_{2-x}$Se${}_2$
• Do Se vacancies electron dope monolayer FeSe?
• Spin fluctuations and superconductivity in KxFe{2-y}Se2
• Superconductivity and Nematic Fluctuations in a model of FeSe monolayers: A Determinant Quantum Monte Carlo Study
• Simultaneous emergence of superconductivity, inter-pocket scattering and nematic fluctuation in potassium-coated FeSe superconductor
• Impurity states in multiband s-wave superconductors: analysis of iron pnictides
• Observation of an electron band above the Fermi level in FeTe${}_{0.55}$Se${}_{0.45}$ from \emph{in-situ} surface doping
• Bounds on Nanoscale Nematicity in Single-Layer FeSe/SrTiO${}_3$
• Effect of nonmagnetic impurities on $s_{\pm }$ superconductivity in the presence of incipient bands
• Ab-initio Studies of (Li${}_{0.8}$Fe${}_{0.2}$)OHFeSe Superconductors: Revealing the Dual Roles of Fe${}_{0.2}$ in Structural Stability and Charge Transfer
• Scanning tunneling spectroscopy as a probe of multi-Q magnetic states of itinerant magnets

Cited by in corpus (97)

• 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
• Higher Order Topology and Nodal Topological Superconductivity in Fe(Se,Te) Heterostructures
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Exotic Superconducting States in FeSe-based Materials
• Pure Spin Photocurrent in Non-centrosymmetric Crystals: Bulk Spin Photovoltaic Effect
• Berry connection polarizability tensor and third-order Hall effect
• Dynamic interfacial polaron enhanced superconductivity of FeSe/SrTiO3
• Experimental Demonstration of the Sign Reversal of the Order Parameter in (Li1-xFex)OHFe1-yZnySe
• Resilient nodeless $d$-wave superconductivity in monolayer FeSe
• Electron phonon coupling versus photoelectron energy loss at the origin of replica bands in photoemission of FeSe on SrTiO${}_3$
• Electronic nematic states tuned by isoelectronic substitution in bulk FeSe1-xSx
• Suppression of superconductivity and enhanced critical field anisotropy in thin flakes of FeSe
• Antiferromagnetism induced by electron-phonon-coupling
• Evolution of spin excitations from bulk to monolayer FeSe
• Antiferromagnetic order in epitaxial FeSe films on SrTiO3
• Strain-tuning of nematicity and superconductivity in single crystals of FeSe
• Threefold enhancement of superconductivity and the role of field-induced odd-frequency pairing in epitaxial aluminum films near the 2D limit
• Observation of Interface Superconductivity in a SnSe2-Epitaxial Graphene van der Waals Heterostructure
• Superconductivity without inversion and time-reversal symmetries
• Magic angles and correlations in twisted nodal superconductors
• Topological Superconductivity in an s-wave Superconductor and Its Implication to Iron-based Superconductors
• Robustness of Antiferromagnetism in the Su-Schrieffer-Heeger-Hubbard model
• Evidence for d-wave superconductivity in single layer FeSe/SrTiO3 probed by quasiparticle scattering off step edges
• Effects of high energy proton irradiation on the superconducting properties of Fe(Se,Te) thin films
• Lattice Dynamics of Ultrathin FeSe Films on SrTiO3
• Nonadiabatic Born effective charges in metals and the Drude weight
• Ab initio phonon self-energies and fluctuation diagnostics of phonon anomalies: Lattice instabilities from Dirac pseudospin physics in transition metal dichalcogenides
• Bulk superconductivity and role of fluctuations in the iron-based superconductor FeSe at high pressures
• Quantum geometric effect on Fulde-Ferrell-Larkin-Ovchinnikov superconductivity
• Itinerant approach to magnetic neutron scattering of FeSe: effect of orbital selectivity
• Heterostructural one-unit-cell FeSe/SrTiO3: from high-temperature superconductivity to topological states
• Superconductivity in monolayer FeSe enhanced by quantum geometry
• Eliashberg theory for spin-fluctuations mediated superconductivity -- Application to bulk and monolayer FeSe
• Classification of Symmetry Derived Pairing at M Point in FeSe
• Tuning stoichiometry and its impact on superconductivity of monolayer and multilayer FeSe on SrTiO3
• Theoretical study of impurity-induced magnetism in FeSe
• Unconventional pairing in single FeSe layers
• Electronic and phononic properties of a two dimensional electron gas coupled to dipolar phonons via small-momentum-transfer scattering
• Intrinsic interfacial van der Waals monolayers and their effect on the high-temperature superconductor FeSe/SrTiO${}_3$
• Increased Performance of Matsubara space calculations: A case study within Eliashberg theory
• Intertwined spin-orbital coupled orders in the iron-based superconductors
• High-Temperature Anomalous Metal States in Iron-Based Interface Superconductors
• FeSe and the missing electron pocket problem
• Superconductivity of anomalous pseudospin
• Soft phonons in the interface layer of the STO substrate can explain high temperature superconductivity in one unit cell FeSe
• Twisted-bilayer FeSe and the Fe-based superlattices
• Towards exact solutions for the superconducting $T_c$ induced by electron-phonon interaction
• Controlling unconventional superconductivity in artificially engineered $f$-electron Kondo superlattices
• Topological d-wave superconductivity in two dimensions
• Superconductivity enhanced by pair fluctuations between wide and narrow bands
• Tuning the pairing interaction in a $d$-wave superconductor by paramagnons injected through interfaces
• Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates
• The Coulomb problem in iron based superconductors
• Identification of a Large Amount of Excess Fe in Superconducting Single-Layer FeSe/SrTiO3 Films
• Molecular beam epitaxy of superconducting FeSe${}_x$Te${}_{1-x}$ thin films interfaced with magnetic topological insulators
• Two-Dimensional Superconductivity at the Titanium Sesquioxide Heterointerface
• Tuning vortex fluctuations and the resistive transition in superconducting films with a thin overlayer
• Relationships between Superconductivity and Nematicity in FeSe${}_{1-x}$Te${}_x$ ($x=0-0.5$) Films Studied by Complex Conductivity Measurements
• Stoichiometry and defect superstructures in epitaxial FeSe films on SrTiO3
• Nodal topology in $d$-wave superconducting monolayer FeSe
• 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
• High-$T_c$ Berezinskii-Kosterlitz-Thouless transition in 2D superconducting systems with coupled deep and quasi-flat electronic bands with van Hove singularities
• Checkerboard order state in superconducting FeSe/SrTiO3(001) monolayer
• Orbital-Selective High-Temperature Cooper Pairing Developed in the Two-Dimensional Limit
• Pairing enhanced by local orbital fluctuations in a model for monolayer FeSe
• Insulating Parent Phase and Distinct Doping Evolution to Superconductivity in Single-Layer FeSe/SrTiO3 Films
• Strong enhancement of magnetic order from bulk to stretched monolayer FeSe as Hund's metals
• Robust d-wave superconductivity from the Su-Schrieffer-Heeger-Hubbard model: possible route to high-temperature superconductivity
• Orbital selectivity versus Pomeranchuk instability in the iron-chalcogenide superconductors: A two-loop renormalization group study
• Nonlinear optical responses in superconductors under magnetic fields: quantum geometry and topological superconductivity
• Imaging Se diffusion across the FeSe/SrTiO${}_3$ interface
• Unusual Effects of Be doping in the Iron Based Superconductor FeSe
• Superfluid drag between excitonic polaritons and superconducting electron gas
• Capping effects on spin and charge excitations in parent and superconducting Nd1-xSrxNiO2
• Strong pairing in two dimensions: Pseudogaps, domes, and other implications
• Optimizing the Critical Temperature and Superfluid Density of a Metal-Superconductor Bilayer
• Tunable superconductivity in Fe-pnictide heterointerfaces by diffusion control
• Doping asymmetry and layer-selective metal-insulator transition in trilayer K${}_{3+x}$C${}_{60}$
• Modification of magnetic fluctuations by interfacial interactions in artificially engineered heavy-fermion superlattices
• Temperature dependence and limiting mechanisms of the upper critical field of FeSe thin films
• Unique properties of the optical activity in noncentrosymmetric superconductors: sum rule, missing area, and relation with the superconducting Edelstein effect
• Atomic-scale analysis of disorder by similarity learning from tunneling spectroscopy
• Twisted Nodal Superconductors
• LaO as a candidate substrate for realizing superconductivity in FeSe epitaxial film
• Enhancing the hybridization of plasmons in graphene with 2D superconductor collective modes
• Studies of superconductivity of Fe chalcogenides in films grown by PLD technique
• Topological Aspects of Antiferromagnets
• Higher-Order Topology in Monolayer FeSe
• Dynamical Coulomb Blockade as a Signature of the Sign-Reversing Cooper Pairing Potential
• Meissner Effect and Nonreciprocal Charge Transport in Non-Topological 1T-CrTe2/FeTe Heterostructures
• Strong enhancements to superconducting properties of 1D systems from metallic reservoirs
• Anisotropic superconductivity induced at a hybrid superconducting-semiconducting interface