Related papers: On the Superconductivity of LaFe1-yCoyAsO1-xFx
To explore the origin of the unusual non-bulk superconductivity with a Tc up to 49 K reported in the rare-earth-doped CaFe2As2 , the chemical composition, magnetization, specific heat, resistivity, and annealing effect are systematically…
We study the transition temperature Tc(H) of a quasi-one-dimensional (Q1D) superconductivity which is derived from the quantum effect of an electron motion in a strong magnetic field. We calculate Tc(H) of both isotropic and anisotropic…
We systematically studied the transport properties of single crystals of $Eu_{1-x}Sr_xFe_{2-y}$Co$_{y}As_2$. Co doping can suppress the spin-density wave (SDW) ordering and induces a superconducting transition, but a resistivity reentrance…
We use neutron scattering to study the structural distortion and antiferromagnetic (AFM) order in LaFeAsO$_{1-x}$F$_{x}$ as the system is doped with fluorine (F) to induce superconductivity. In the undoped state, LaFeAsO exhibits a…
A series of high quality NaFe$_{1-x}$Cu$_x$As single crystals has been grown by a self-flux technique, which were systematically characterized via structural, transport, thermodynamic, and high pressure measurements. Both the structural and…
$^{19}$F NMR measurements in SmFeAsO$_{1-x}$F$_x$, for $0.15\leq x\leq 0.2$, are presented. The nuclear spin-lattice relaxation rate $1/T_1$ increases upon cooling with a trend analogous to the one already observed in…
Temperature (T) dependence of 59Co-NMR Knight shifts K of Na0.3CoO2.1.3H2O has been studied, where samples of randomly oriented powder and aligned crystals have been used for the applied magnetic fields H // ab plane and H //c-axis,…
We have studied the newly found superconductor compound LaO$_{1-x}$F$_x$FeAs through the first-principles density functional theory calculations. We find that the parent compound LaOFeAs is a quasi-2-dimensional antiferromgnetic semimetal…
We use $^{75}$As nuclear magnetic resonance (NMR) to investigate the local electronic properties of Ba(Fe$_{1-x}$Ru$_{x}$)$_2$As$_2$ ($x =$ 0.23). We find two phase transitions, to antiferromagnetism at $T_N \approx$ 60 K and to…
We use spatially-resolved transport techniques to investigate the superconducting properties of single crystals La$_{2-x}$Ba$_x$CuO$_4$. We find a new superconducting transition temperature $T_{cs}$ associated with the ab-plane surface…
Superconductivity has been observed in doped SrTiO$_3$ at charge-carrier densities below 10$^{18}$ cm$^{-3}$, where the density of states at the Fermi level of the itinerant electrons is several orders of magnitude lower than that of…
The nature and value of the order parameters (OPs) in the superconducting Fe-based oxypnictides REFeAsO_(1-x)F_x (RE = rare earth) are a matter of intense debate, also connected to the pairing mechanism which is probably unconventional.…
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…
We study hydrogen doping effects in an iron-based superconductor LaFeAsO_(1-y) by using the first-principles calculation and explore the reason why the superconducting transition temperature is remarkably enhanced by the hydrogen doping.…
The characteristics of Fe-based superconductors are manifested in their electronic, magnetic properties, and pairing symmetry of the Cooper pair, but the latter remain to be explored. Usually in these materials, superconductivity coexists…
We have investigated the magnetism and the superconductivity of an electron-doped Pr$_{1-x}$LaCe$_{x}$CuO$_{4}$ (PLCCO) using single crystal and powder samples by means of zero-field muon spin rotation/relaxation (ZF-$\mu$SR) and magnetic…
We use neutron scattering to study the spin and lattice structures of single crystal and powder samples of Na$_{1-\delta}$FeAs ($T_c = 23$ K). On cooling from room temperature, the system goes through a series of phase transitions: first…
We have carried out detailed magnetic and transport studies of the new Sr0.5Ce0.5FBiS2-xSex (x = 0.5, 1) superconductors derived by doping Se in Sr0.5Ce0.5FBiS2. Se-doping produces several effects: it suppresses semiconducting like behavior…
We have successfully synthesized the fluoride-arsenide compounds Ca$_{1-x}$RE$_x$FeAsF (RE=Nd, Pr; x=0, 0.6). The x-ray powder diffraction confirmed that the main phases of our samples are Ca$_{1-x}$RE$_x$FeAsF with the ZrCuSiAs structure.…
Here, we present an electrical transport study in single crystals of LaFe$_{0.92}$Co$_{0.08}$AsO ($T_c \simeq 9.1$ K) under high magnetic fields. In contrast to most of the previously reported Fe based superconductors, and despite its…