Hazuki Kawano-Furukawa

Coexistence of Superconductivity and (Anti-)Ferromagnetism in RuSr2YCu2O8.

The coexistence of antiferromagnetism and superconductivity in the hybrid ruthenate-cuprate RuSr 2 YCu 2 O 8 synthesized under high pressure has been confirmed by means of powder neutron diffraction and resistivity measurements. The Ru moments are antiferromagnetically ordered at about 149 K and Ru spins can be aligned by applying a magnetic field, suggesting that the system gradually changes from antiferromagnetism to ferromagnetism. However, the superconductivity in the compound persists even at H =9 T. This indicates the coexistence of ferromagnetism and superconductivity under a high magnetic field.

Incommensurate spin fluctuations in hole-overdoped superconductor KFe2As2.

A neutron scattering study of heavily hole-overdoped superconducting KFe2As2 revealed a well-defined low-energy incommensurate spin fluctuation at [π(1 ± 2 δ),0] with δ = 0.16. The incommensurate structure differs from the previously observed commensurate peaks in electron-doped AFe2As2 (A = Ba, Ca, or Sr) at low energies. The direction of the peak splitting is perpendicular to that observed in Fe(Te,Se) or in Ba(Fe,Co)2As2 at high energies. A band structure calculation suggests interband scattering between bands around the Γ and X points as an origin of this incommensurate peak. The perpendicular direction of the peak splitting can be understood within the framework of multiorbital band structure. The results suggest that spin fluctuation is more robust in hole-doped than in electron-doped samples, which can be responsible for the appearance of superconductivity in the heavily hole-doped samples.

Gap in KFe2As2studied by small-angle neutron scattering observations of the magnetic vortex lattice

We report the observation, by small-angle-neutron-scattering (SANS), of magnetic flux lines “vortices” in super-clean KFe2As2 single crystals. The results show clear Bragg spots from a well ordered vortex lattice, for the first time in a FeAs superconductor. These measurements can give important information about the pairing state in this material, because the spatial variation of magnetic field in the vortex lattice reflects this pairing. With field parallel to the fourfold c-axis, nearly isotropic hexagonal packing of vortices was observed without VL-symmetry transitions up to high fields, indicating rather small anisotropy of the superconducting properties around this axis. This rules out gap nodes parallel to the c-axis, and thus d-wave and also anisotropic s-wave pairing. The strong temperature-dependence of the scattered intensity down to T Tc further indicates either widely different full gaps on different Fermi surface sheets, or nodal lines perpendicular to the axis. PACS numbers: 74.25.Uv, 74.70.Xa, 74.20.Rp, 74.25.-q

Competition between unconventional superconductivity and incommensurate antiferromagnetic order in Ce Rh 1 − x Co x In 5

Elastic neutron diffraction measurements were performed on the quasi-two-dimensional heavy-fermion system

Orbital-ordering-induced anomalous softening of the ferromagnetic spin waves in perovskite manganites

\mathrm{Ce}{\mathrm{Rh}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{In}}_{5}

Magnetic field-induced quasiparticle excitation in Nb 3 Sn: Evidence for anisotropic s-wave pairing

, ranging from an incommensurate antiferromagnet for low Co composition

Anomalous Flux Line Lattice in CeCoIn5

x

Vortex lattice structure in BaFe2(As0.67P0.33)(2) via small-angle neutron scattering

to an unconventional superconductor on the Co-rich end of the phase diagram. We found that the superconductivity competes with the incommensurate antiferromagnetic (AFM) order characterized by

H‐T Phase Diagram of Flux Line Lattice Structure in YNi2B2C

{\mathbit{q}}_{I}=(1∕2,1∕2,\ensuremath{\delta})

Vortex lattice structure inBaFe2(As0.67P0.33)2via small-angle neutron scattering

with