相关论文: Hydration-induced anisotropic spin fluctuations in…

We report the first ^{75}As-NMR study on a single crystal of the hole-doped iron-pnictide superconductor Ba_{0.7}K_{0.3}Fe_2As_{2} (T_c = 31.5 K). We find that the Fe antiferromagnetic spin fluctuations are anisotropic and are weaker…

We probed the local electronic properties of the mixed-valent Co(+4-x) triangular-lattice in Na{x}CoO{2}-yH{2}O by 59-Co NMR. We observed two distinct types of Co sites for x>=1/2, but the valence seems averaged out for x~1/3. Local spin…

We report electronic structure calculations within density functional theory for the hydrated superconductor Na_{1/3}CoO_2(1.33)H_2O and compare the results with the parent compound Na_{0.3}CoO_2. We find that the intercalation of water…

We use unpolarized and polarized neutron scattering to study the temperature and polarization dependence of low-energy magnetic fluctuations in nearly-optimal-doped NaFe$_{0.9785}$Co$_{0.0215}$As, with coexisting superconductivity ($T_{\rm…

Motivated by recent experiments on isovalent-doped 1111 iron-based superconductors LaFeAs$_{1-{x}}$P$_{x}$O$_{1-{y}}$F$_{y}$ and the theoretical study that followed, we investigate, within the five orbital model, the correlation between the…

We report Raman scattering experiments on the strongly correlated electron system NaxCoO2 with x= 0.71 and ordered Na vacancies. In this doping regime, NaxCoO2 exhibits a large and unusual thermopower and becomes superconducting upon…

Since its discovery, the superconducting phase in water-intercalated sodium cobaltates NaxCoO2 yH2O (x~0.3, y~1.3) has posed fundamental challenges in terms of experimental investigation and theoretical understanding. By a combined…

Various samples of sodium cobalt oxyhydrate with relatively large amounts of Na$^{+}$ ions were synthesized by a modified soft-chemical process in which a NaOH aqueous solution was added in the final step of the procedure. From these…

Despite the recent discovery of superconductivity in Nd$_{1-x}$Sr$_{x}$NiO$_2$ thin films, the absence of superconductivity and antiferromagnetism in their bulk materials remain a puzzle. Here we report the $^{1}$H NMR measurements on…

We report the in-plane resistivity and magnetic susceptibility of the layered cobalt oxide Na$_{0.35}$CoO$_{2}{\cdot}1.3$H$_{2}$O single crystal. The temperature dependence of the resistivity shows metallic behavior from room temperature to…

Elucidating spin correlations in the parent compounds of high-temperature superconductors is crucial for understanding superconductivity. We used neutron scattering to study spin correlations in Li$_{1-x}$Fe$_x$ODFeSe, an insulating…

The specific heats of three samples of Na0.35CoO2,1.3H2O show an evolution of the superconductivity, and its ultimate disappearance, with increasing sample age. An overall increase in pair-breaking action, which occurs preferentially in an…

We succeeded in synthesizing the powder samples of bilayer-hydrate sodium cobalt oxide superconductors NaxCoO2-yH2O with Tc = 0 ~ 4.6 K by systematically changing the keeping duration in a 75 % relative humidity atmosphere after…

We propose that unconventional superconductivity in hydrated sodium cobaltate $Na_xCoO_2$ results from an interplay of electronic correlations and electron-phonon interactions. On the basis of the $t-V$ model plus phonons we found evidences…

Using first-principles electronic structure calculations, we have extensively studied the electronic and magnetic properties of alkali sodium superoxide (NaO2) in comparison with that of potassium superoxide (KO2) both at high and low…

We report on a Raman scattering study on the superconducting cobaltite $Na_xCoO_2\cdot yH_2O$ as function of Na content and hydration (x$\approx$1/3, 3/4 and y$\approx$0, 2/3, 4/3). The observed phonon scattering and scattering continua are…

To investigate the superconducting (SC) state near a charge instability, we performed ^{13}C NMR experiments on the molecular superconductor beta"-(BEDT-TTF)_{4}[(H_{3}O)Ga(C_{2}O_{4})_{3}]C_{6}H_{5}NO_{2}, which exhibits a charge anomaly…

Motivated by recent nuclear magnetic resonance experiments, we calculated the spin susceptibility, Knight shift, and spin-lattice relaxation rate ($1/T_{1}T$) of the single-component molecular conductor [Ni(dmdt)$_2$] using the random phase…

We report on systematic evolutions of antiferromagnetic (AFM) spin fluctuations and unconventional superconductivity (SC) in heavy-fermion (HF) compounds CeRh$_{1-x}$Ir$_{x}$In$_5$ via $^{115}$In nuclear-quadrupole-resonance (NQR)…

Overdoped cuprate superconductors are strange metals above their superconducting transition temperature. In such materials, the electrical resistivity has a strong linear dependence on temperature ($T$) and electrical current is not carried…