Related papers: Strong-coupling Spin-singlet Superconductivity wit…
The recent discovery of superconductivity in iron-arsenic compounds below a transition temperature (Tc) as high as 55K ended the monopoly of copper oxides (cuprates) in the family of high-Tc superconductors. A critical issue in…
We report a ^{125}Te-NMR study of single-crystalline Pb_{1-x}Tl_{x}Te for x= 0 (undoped non-superconducting "parent"), 0.35 at% (doped but on the borderline of superconductivity), and 1.0 at% (superconducting, with a critical temperature Tc…
We report the specific heat (SH) measurements on single crystals of hole doped $FeAs$-based superconductor $Ba_{0.6}K_{0.4}Fe_2As_2$. It is found that the electronic SH coefficient $\gamma_e(T)$ is not temperature dependent and increases…
Spin excitations stemming from the metallic phase of the ferrochalcogenide superconductor K(0.77)Fe(1.85)Se(2) (T_c=32 K) were mapped out in the ab plane by means of the time-of-flight neutron spectroscopy. We observed a magnetic resonant…
FeSe is arguably the simplest, yet the most enigmatic, iron-based superconductor. Its nematic but non-magnetic ground state is unprecedented in this class of materials and stands out as a current puzzle. Here, our NMR measurements in the…
Polarized inelastic neutron scattering experiments were performed to study magnetic excitations in the normal and superconducting phases of Co-underdoped BaFe$_2$As$_2$, which exhibits coexistence of antiferromagnetic order and…
We report measurements of the ^{115}In nuclear spin-lattice relaxation rate (1/T_1) between T=0.09 K and 100 K in the new heavy fermion (HF) compound CeIrIn_5. At 0.4 K < T < 100 K, 1/T_1 is strongly T-dependent, which indicates that…
We systematically investigate the photoexcited (PE) quasi-particle (QP) relaxation and low-energy electronic structure in electron doped Ba(Fe_{1-x}Co_{x})_{2}As_{2} single crystals as a function of Co doping, 0<= x <=0.11. The evolution of…
We report a detailed study of $^{11}$B and $^{27}$Al NMR spin-lattice relaxation rates ($1/T_1$), as well as of $^{27}$Al Knight shift (K) of Mg$_{1-x}$Al$_x$B$_2$, $0\leq x\leq 1$. The obtained ($1/T_1T$) and K vs. x plots are in excellent…
Temperature-dependent inter-plane resistivity, $\rho _c(T)$, was used to characterise the normal state of the iron-arsenide superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ over a broad doping range $0\leq x<0.50$. The data were compared with…
Nuclear magnetic resonance (NMR) measurements on the $^{195}$Pt nucleus in an aligned powder of the moderately heavy-fermion material U2PtC2 are consistent with spin-triplet pairing in its superconducting state. Across the superconducting…
We have performed inelastic neutron scattering measurements on a powder sample of the superconductor lithium iron selenide hydroxide Li$_{1-x}$Fe$_{x}$ODFe$_{1-y}$Se ($x \simeq 0.16, y \simeq 0.02$, $T_{\rm c} = 41$\,K). The spectrum shows…
Using polarization-resolved electronic Raman scattering we study under-doped, optimally-doped and over-doped Ba$_{1-x}$K$_{x}$Fe$_2$As$_2$ samples in the normal and superconducting states. We show that low-energy nematic fluctuations are…
We report the results from a thermopower and a Cu nuclear magnetic resonance (NMR) study of the infinite CuO2 layer electron doped high temperature superconducting cuprate (HTSC), Sr0.9La0.1CuO2. We find that the temperature dependence of…
While unusual normal state properties, such as non-Fermi liquid behavior of the resistivity, are commonly associated with strong quantum fluctuations, evidence for its presence inside the superconducting dome are much scarcer. In this…
We investigate interplay between magnetic fluctuations and superconductivity in the effective five-band Hubbard model for iron-oxypnictide superconductors on the basis of the fluctuation-exchange approximation. As for the normal-state…
Neutrons have played an important role in advancing our understanding of the pairing mechanism and the symmetry of the superconducting energy gap in the iron arsenide compounds. Neutron measurements of the phonon density-of-state are in…
Similar to the cuprate high TC superconductors, the iron pnictide superconductors also lie in close proximity to a magnetically ordered phase. A central debate concerning the superconducting mechanism is whether the local magnetic moments…
Infrared reflectivity measurements on 122 iron-pnictides reveal the existence of two electronic subsystems. The one gapped due to the spin-density-wave transition in the parent materials, such as EuFe$_2$As$_{2}$, is responsible for…
We have performed powder inelastic neutron scattering measurements on the unconventional superconductor $\beta$-FeSe ($T_{\rm c} \simeq 8\,\mathrm{K}$). The spectra reveal highly dispersive paramagnetic fluctuations emerging from the…