相关论文: Evolution of the neutron resonances in AFe2Se2
Based on an effective 12-orbital tight-binding model, we examine the superconducting states induced by the antiferromagnetic fluctuations for iron-vacancy-ordered A$_{y}$Fe$_{2-x}$Se$_{2}$. It is shown that due to the broken reflection…
Motivated by the premise that superconductivity in iron-based superconductors is unconventional and mediated by spin fluctuations, an intense research effort has been focused on characterizing the spin excitation spectrum in the…
Infrared reflectance measurements were made with light polarized along the a- and c-axis of both superconducting and antiferromagnetic phases of electron doped Nd$_{1.85}$Ce$_{.15}$CuO$_{4+\delta}$. The results are compared to…
Electronic scattering is a powerful tool to identify underlying changes in electronic behavior and incipient electronic and magnetic orders. The nematic and magnetic phases are strongly intertwined under applied pressure in FeSe, however,…
We have used inelastic neutron scattering and muon-spin rotation to compare the low energy magnetic excitations in single crystals of superconducting Fe1.01Se0.50Te0.50 and non-superconducting Fe1.10Se0.25Te0.75. We confirm the existence of…
We focus on inelastic neutron scattering in $URu_2Si_2$ and argue that observed gap in the fermion spectrum naturally leads to the spin feature observed at energies $\omega_{res} = 4-6 meV$ at momenta at $\bQ^* = (1\pm 0.4, 0,0)$. We…
Spin-fluctuation-mediated superconductivity is conventionally associated with d_{x^2-y^2} pairing. We show that a generalized model of antiferromagnetic spin fluctuations in three dimensions may also yield a state with formal ``s-wave''…
We use polarized inelastic neutron scattering to show that the neutron spin resonance below $T_c$ in superconducting BaFe$_{1.9}$Ni$_{0.1}$As$_2$ ($T_c=20$ K) is purely magnetic in origin. Our analysis further reveals that the resonance…
The results of neutron scattering and angle-resolved photoemission experiments for the Fe-pnictide parent compounds, and their metallic nature, are shown to impose severe constraints on the range of values that can be considered "realistic"…
An antiferromagnetic (AF) spin fluctuation induced pairing model is proposed for the electron-doped cuprate superconductors. It suggests that, similar to the hole-doped side, the superconducting gap function is monotonic d_{x^2-y^2}-wave…
Superconductivity was recently observed in boron-doped ($\sqrt{3}\times\sqrt{3}$)Sn/Si(111). The material can be described by an extended Hubbard model on a triangular lattice. Here, we use the random-phase approximation to investigate the…
We present a comprehensive set of elastic and inelastic neutron scattering measurements on a range of Fe-doped samples of U(Ru$_{1-x}$Fe$_x$)$_2$Si$_2$ with 0.01~$\le~x~\le$~0.15. All of the samples measured exhibit long-range…
Studies of Hamiltonians modeling the coupling between electrons as well as to local phonon excitations have been fundamental in capturing the novel ordering seen in many quasi-one dimensional condensed matter systems. Extending studies of…
We introduce a variational state for one-dimensional two-orbital Hubbard models that intuitively explains the recent computational discovery of pairing in these systems when hole doped. Our Ansatz is an optimized linear superposition of…
We study the ground state properties of the hole-doped three-band Hubbard (Emery) model, describing the copper-oxygen planes of the cuprates, using large-scale 2D tensor network calculations. Our simulations reveal a period 4 stripe state…
We consider the spin response within the five-orbital model for iron-based superconductors and study two cases: equal and unequal gaps in different bands. In the first case, the spin resonance peak in the superconducting state appears below…
Hidden spin-density waves (hSDW) with Neel ordering vector (pi,pi) have been proposed recently as parent groundstates to electron-doped iron-selenide superconductors. Doping such groundstates can result in visible electron-type Fermi…
From heavy fermions to cuprates and iron pnictides, a spin resonance is a staple of nearly magnetic superconductors. Possible explanations include a two-particle bound state or loss of magnon damping in the superconductor. While both…
Spin fluctuations are considered to be one of the candidates that drive a sign-reversed s^{\pm} superconducting state in the iron pnictides. In the magnetic scenario, whether the spin fluctuation spectrum exhibits certain unique fine…
We analyze the evolution of the superconducting gap structure in strongly hole doped Ba_{1-x}K_xFe_2As_2 between x=1 and x ~ 0.4 (optimal doping). In the latter case, the pairing state is most likely s+-, with different gap signs on hole…