Related papers: Feedback spin resonance in superconducting CeCu$_2…
We use neutron spectroscopy to determine the nature of the magnetic excitations in superconducting BaFe$_{1.9}$Ni$_{0.1}$As$_{2}$ ($T_{c}=20$ K). Above $T_{c}$ the excitations are gapless and centered at the commensurate antiferromagnetic…
Neutron scattering in strong magnetic fields is used to show the spin-resonance in superconducting CeCoIn5 (Tc=2.3 K) is a doublet. The underdamped resonance (\hbar \Gamma=0.069 \pm 0.019 meV) Zeeman splits into two modes at E_{\pm}=\hbar…
The heavy-fermion metal CeCu$_2$Si$_2$ was the first discovered unconventional, non-phonon-mediated superconductor, and for a long time was believed to exhibit single-band $d$-wave superconductivity, as inferred from various measurements…
Recent experiments on CeCoIn5 -- a prototypical d-wave superconductor -- indicate that its normal state lies near an unconventional quantum critical point (QCP). One intriguing hypothesis is that quantum-critical fluctuations promote…
The dynamical spin susceptibility in the new-structure-type iron-based superconductor CaKFe$_4$As$_4$ was investigated by using a combination of inelastic neutron scattering (INS) measurements and random phase approximation (RPA)…
We investigate the quasiparticle interference in the heavy Fermion superconductor CeCoIn_5 as direct method to confirm the d-wave gap symmetry. The ambiguity between d_{xy} and d_{x^2-y^2} symmetry remaining from earlier specific heat and…
The origin of the spin resonance observed in CeCoIn5 with Inelastic Neutron Scattering is subject to debate. It has been shown recently that in this heavy electron compound at low temperature an instability to a ground state with coexisting…
We study spin resonance in the superconducting state of recently discovered alkali-intercalated iron selenide materials A_xFe_(2-y)Se_2 (A=K,Rb,Cs) in which the Fermi surface has only electron pockets. Recent angle-resolved photoemission…
We report field-orientation specific heat studies of the pressure-induced heavy fermion superconductor CeRhIn5. Theses experiments provide the momentum-dependent superconducting gap function for the first time in any pressure-induced…
Quasi-two dimensional CeIrIn5 contains two distinct domes with different heavy fermion superconducting states in its phase diagram. Here we pinned down the superconducting gap structure of CeIrIn5 in the second dome, located away from the…
Neutron scattering measurements are used to elucidate interplay of the field-induced spin gap and the quantum fluctuations in archetypal heavy electron system CeCu$_{2}$Ge$_{2}$. A spin gap of $\Delta$ = 0.56 meV is found to develop near…
We propose the multiband extension of the spin-fermion model to address the superconducting d-wave pairing due to magnetic interaction near critical point. We solve the unrestricted gap equation with a general d-wave symmetry gap and find…
It is shown by detailed inelastic neutron scattering experiments that the gapped collective magnetic excitation of the unconventional superconductor CeCoIn$_{5}$, the spin resonance mode, is incommensurate and that the corresponding…
In zero magnetic field, the famous neutron spin resonance in the f-electron superconductor CeCoIn5 is similar to the recently discovered exciton peak in the non-superconducting CeB6. Magnetic field splits the resonance in CeCoIn5 into two…
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…
Based on the effective four-band model we analyze the spin response in the normal and superconducting states of the Fe-pnictide superconductors. While the normal state spin excitations are dominated by the continuum of the interorbital…
The implications of the spin exciton mechanism are exposed in the context of a Spin Density Wave (SDW) instability occurring inside the superconducting phase of a layered heavy electron compound. In this model a magnetic field serves as a…
We present scanning tunneling spectroscopy measurements of the local quasiparticles' excitation spectra of CeCoIn$_5$ between 440mK and 3K in samples with a bulk $T_{\rm c}=2.25$K. The spectral shape of our low-temperature tunneling data,…
We theoretically study the effect of a nonmagnetic impurity in heavy fermion superconductor CeCoIn$_{5}$ within a realistic band model and the T-matrix approximation approach. By considering two known possible pairing symmetry candidates…
The heavy-fermion superconductor CeCu$_{2}$Si$_{2}$ exhibits two-band, $d$-wave superconductivity with a finite energy gap over the whole Fermi surface around the magnetic instability where 4$f$ antiferrerromagnetic order is suppressed. In…