Related papers: Insular superconductivity in Co-doped iron pnictid…
Possible superconductivity in recently discovered (Tl,K)Fe$_x$Se$_2$ compounds is studied from the viewpoint of doped Mott insulator. The Mott insulating phase is examined to be preferred in the parent compound at $x=1.5$ due to the…
Superconductors usually display either type-I or type-II superconductivity and the coexistence of these two types in the same material, for example at different temperatures is rare in nature. We the employed muon spin rotation (muSR)…
The discovery of alkaline iron selenide $A$Fe$_{1.6+x}$Se$_2$ ($A=$ K, Rb, Cs) superconductors has generated considerable excitement in the condensed matter physics community because superconductivity in these materials may have a different…
We report the resistivity of a series of fluorine-doped SmFeAsO1-xFx polycrystalline superconductors in magnetic fields up to 60T. For underdoped samples (x < 0.15), the low temperature resistive state is characterized by pronounced…
We explore if the phase separation or coexistence of the spin density wave (SDW) and superconductivity (SC) states has any relation to the incommensurability of the SDW in the Fe pnictide superconductors. A systematic method of determining…
High-temperature superconductivity in iron-arsenic materials (pnictides) near an antiferromagnetic phase raises the possibility of spin-fluctuation-mediated pairing. However, the interplay between antiferromagnetic fluctuations and…
The interplay of magnetism and superconductivity (SC) has been a focus of interest in condensed matter physics for decades. EuFe2As2 has been identified as a potential platform to investigate interactions between structural, magnetic,…
A new hight Tc Fe-based compound system, AFe2As2 with A = K, Cs, K/Sr and Cs/Sr has been found. Through electron-doping, Tc of the A = K and Cs compounds rises to ~37 K, and finally enter a spin-density-wave state (SDW) through further…
We investigate the physical properties and electronic structure upon Cr-doping in the iron arsenide layers of BaFe2As2. This form of hole-doping leads to suppression of the magnetic/structural phase transition in BaFe2-xCrxAs2 for x > 0,…
We report on isofield magnetization curves obtained as a function of temperature in two single crystals of $Ba_{1-x}K_xFe_2As_2$ with superconducting transition temperature $T_c$=28K and 32.7 K. Results obtained for fields above 20 kOe show…
High temperature superconductivity is a property of doped antiferromagnetic insulators. The electronic structure is inhomogeneous on short length and time scales, and, as the temperature decreases, it evolves via two crossovers, before long…
Recent nuclear magnetic resonance (NMR) measurements revealed the coexistence of stripe-type antiferromagnetic (AFM) and ferromagnetic (FM) spin correlations in both the hole- and electron-doped BaFe$_2$As$_2$ families of iron-pnictide…
We report synthesis, structural details and magnetization of SmFe1-xCoxAsO with x ranging from 0.0 to 1.0 at close interval of 0.10. It is found that Co substitutes fully at Fe site in SmFeAsO in an iso-structural lattice with slightly…
The discovery of superconductivity in alkali-ammonia co-intercalated FeSe has generated intensive interest because of their highest Tc (~ 45 K) among iron-chalcogenide superconductors with bulk form. Here, we report the phase diagrams of…
The microscopic details of flux line lattice state studied by muon spin rotation is reported in an electron-doped high-$T_{\rm c}$ cuprate superconductor, Sr$_{1-x}$La$_{x}$CuO$_{2}$ (SLCO, $x=0.10$--0.15). A clear sign of phase separation…
We use time-of-flight (ToF) inelastic neutron scattering (INS) spectroscopy to investigate the doping dependence of magnetic excitations across the phase diagram of NaFe$_{1-x}$Co$_x$As with $x=0, 0.0175, 0.0215, 0.05,$ and $0.11$. The…
We report the results of a systematic investigation of the phase diagram of the iron-based superconductor, Ba1-xKxFe2As2, from x = 0 to x = 1.0 using high resolution neutron and x-ray diffraction and magnetization measurements. The…
A hallmark of the iron-based superconductors is the strong coupling between magnetic, structural and electronic degrees of freedom. However, a universal picture of the normal state properties of these compounds has been confounded by recent…
The recently discovered high-temperature superconductivity in doped quaternary iron oxypnictides correlates experimentally with a magnetic instability. We have used first-principles calculations to determine a magnetic phase diagram of…
We report 75As-NMR/NQR results on new iron-arsenide compounds (La0.5-xNa0.5+x)Fe2As2. The parent compound x=0 exhibits a stripe-type antiferromagnetic (AFM) order below T_N=130 K. The measurement of nuclear spin relaxation rate at…