Role of nematicity in controlling spin fluctuations and superconducting Tc in bulk FeSe

Abstract

FeSe undergoes a transition from a tetragonal to a slightly orthorhombic phase at 90\,K, and becomes a superconductor below 8\,K. The orthorhombic phase is sometimes called a nematic phase because quantum oscillation, neutron, and other measurements detect a significant asymmetry in $x$ and $y$. How nematicity affects superconductivity has recently become a matter of intense speculation. Here we employ an advanced \emph{ab-initio} Green's function description of superconductivity and show that bulk tetragonal FeSe would, in principle, superconduct with almost the same T${}_c$ as the nematic phase. The mechanism driving the observed nematicity is not yet understood. Since the present theory underestimates nematicity, we simulate the full nematic asymmetry by artificially enhancing the orthorhombic distortion. For benchmarking, we compare theoretical spin susceptibilities against experimentally observed data over all energies and relevant momenta. When the orthorhombic distortion is adjusted to correlate with observed nematicity in spin susceptibility, the enhanced nematicity causes spectral weight redistribution in the Fe-3d${}_{xz}$ and d${}_{yz}$ orbitals, but it leads to at most 10-15$\%$ increment in T${}_c$. This is because the d${}_{xy}$ orbital always remains the most strongly correlated and provides most of the source of the superconducting glue. Nematicity suppresses the density of states at Fermi level; nevertheless T${}_c$ increases, in contradiction to both BCS and BEC theories. We show how the increase is connected to the structure of the particle-particle vertex. Our results suggest while nematicity may be intrinsic property of bulk FeSe, is not the primary force driving the superconducting pairing.

arXiv comment10 pages, 5 figures

References in corpus (34)

• 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
• A continuous-time solver for quantum impurity models
• Superconductivity at 27 K in tetragonal FeSe under high pressure
• Quantum Monte Carlo Impurity Solver for Cluster DMFT and Electronic Structure Calculations in Adjustable Base
• Dynamical Mean-Field Theory within the Full-Potential Methods: Electronic structure of Ce-115 materials
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Quasiparticle self-consistent $GW$ method; a basis for the independent-particle approximation
• Effective Coulomb interaction in transition metals from constrained random-phase approximation
• Strong Interplay between Stripe Spin Fluctuations, Nematicity and Superconductivity in FeSe
• Origin of the tetragonal-to-orthorhombic (nematic) phase transition in FeSe: a combined thermodynamic and NMR study
• Nematic quantum critical point without magnetism in FeSe1-xSx superconductors
• Ab-initio procedure for effective models of correlated materials with entangled band structure
• Nematicity, magnetism and superconductivity in FeSe
• Magnetic ground state of FeSe
• The key ingredients of the electronic structure of FeSe
• Spin dynamics and an orbital-antiphase pairing symmetry in iron-based superconductors
• Questaal: a package of electronic structure methods based on the linear muffin-tin orbital technique
• Magnetism, superconductivity, and spontaneous orbital order in iron-based superconductors: who comes first and why?
• Origin of the Resistivity Anisotropy in the Nematic Phase of FeSe
• Maximizing Tc by tuning nematicity and magnetism in FeSe1-xSx superconductors
• Evidence for unidirectional nematic bond ordering in FeSe
• Anisotropic Structure of the Order Parameter in FeSe0.45Te0.55 Revealed by Angle Resolved Specific Heat
• Anisotropic spin fluctuations in detwinned FeSe
• Electronic anisotropies revealed by detwinned ARPES measurements of FeSe
• Quenched nematic criticality separating two superconducting domes in an iron-based superconductor under pressure
• Merging GW with DMFT and non-local correlations beyond
• Self-energies in itinerant magnets: A focus on Fe and Ni
• Revealing the single electron pocket of FeSe in a single orthorhombic domain
• Electron-Phonon-Driven Three-Dimensional Metallicity in an Insulating Cuprate
• Controlling T${}_c$ through band structure and correlation engineering in collapsed and uncollapsed phases of iron arsenides
• Interplay between band structure and Hund's correlation to increase T${}_c$ in FeSe
• Electronic structure correspondence of singlet-triplet scale separation in strained Sr2RuO4
• The Iso-electronic Series $C{a}_{2-x}S{r}_{x}Ru{O}_4$: Structural Distortion, Effective Dimensionality, Spin Fluctuations and Quantum Criticality

Cited by in corpus (5)

• QS$G\hat{W}$: Quasiparticle Self consistent $GW$ with ladder diagrams in $W$
• Electronic nematic states tuned by isoelectronic substitution in bulk FeSe1-xSx
• Second-order phase transitions and divergent linear response in dynamical mean-field theory
• Disentangling the role of bond lengths and orbital symmetries in controlling $T_c$ in YBa${}_2$Cu${}_3$O${}_7$
• Three-dimensional spin susceptibility in Ba${}_{0.75}$K${}_{0.25}$Fe${}_2$As${}_2$: Out-of-plane modulation revealed by neutron spectroscopy and theoretical modeling