A5070433550- Rare-earth and actinide compounds
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Magnetic Properties of Alloys
- Advanced Condensed Matter Physics
- Boron and Carbon Nanomaterials Research
- Multiferroics and related materials
- Superconductivity in MgB2 and Alloys
- Superconducting Materials and Applications
- High-pressure geophysics and materials
- Theoretical and Computational Physics
- Hydrogen Storage and Materials
- Quantum, superfluid, helium dynamics
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Shape Memory Alloy Transformations
- Magnetic properties of thin films
- Topological and Geometric Data Analysis
- Photonic Crystals and Applications
- Quasicrystal Structures and Properties
- Geological and Geophysical Studies
- Inorganic Fluorides and Related Compounds
- Seismology and Earthquake Studies
- Fullerene Chemistry and Applications
Ochanomizu University
2014-2024
RIKEN Center for Emergent Matter Science
2017-2024
Otsuka (Japan)
2001-2017
Japan Science and Technology Agency
2002-2004
RIKEN
2001
A neutron scattering study of heavily hole-overdoped superconducting ${\mathrm{KFe}}_{2}{\mathrm{As}}_{2}$ revealed a well-defined low-energy incommensurate spin fluctuation at [$\ensuremath{\pi}(1\ifmmode\pm\else\textpm\fi{}2\ensuremath{\delta}),0$] with $\ensuremath{\delta}=0.16$. The structure differs from the previously observed commensurate peaks in electron-doped $A{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$ ($A=\mathrm{Ba}$, Ca, or Sr) low energies. direction peak splitting is perpendicular...
Understanding the mechanism and symmetry of electron pairing in iron-based superconductors represents an important challenge condensed matter physics [1-3]. The observation magnetic flux lines - "vortices" a superconductor can contribute to this issue, because spatial variation field reflects pairing. Unlike many other iron pnictides, our KFe2As2 crystals have very weak vortex pinning, allowing small-angle-neutron-scattering (SANS) observations intrinsic lattice (VL). We observe nearly...
The coexistence of antiferromagnetism and superconductivity in the hybrid ruthenate-cuprate RuSr 2 YCu O 8 synthesized under high pressure has been confirmed by means powder neutron diffraction resistivity measurements. Ru moments are antiferromagnetically ordered at about 149 K spins can be aligned applying a magnetic field, suggesting that system gradually changes from to ferromagnetism. However, compound persists even H =9 T. This indicates ferromagnetism field.
We describe the technique of small-angle neutron scattering, as used to image vortex lattice in superconductors, and information that can be gained from this technique. review present state these measurements on iron-based discuss implications results; particular, we compare about pairing compounds with available other techniques.
Neutron scattering results are presented for spin-wave excitations of three ferromagnetic metallic $A_{1-x}A^{\prime}_{x}$MnO$_3$ manganites (where $A$ and $A^\prime$ rare- alkaline-earth ions), which when combined with previous work elucidate systematics the interactions as a function carrier concentration $x$, on-site disorder, strength lattice distortion. The long wavelength spin dynamics show only very weak dependence across series. ratio fourth to first neighbor exchange ($J_4/J_1$)...
Elastic neutron diffraction measurements were performed on the quasi-two-dimensional heavy-fermion system $\mathrm{Ce}{\mathrm{Rh}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{In}}_{5}$, ranging from an incommensurate antiferromagnet for low Co composition $x$ to unconventional superconductor Co-rich end of phase diagram. We found that superconductivity competes with antiferromagnetic (AFM) order characterized by ${\mathbit{q}}_{I}=(1∕2,1∕2,\ensuremath{\delta})$ $\ensuremath{\delta}=0.298$,...
Neutron scattering is a powerful tool to study magnetic structures and cross-correlated phenomena originated from symmetry of the in matter. Among number neutron techniques, polarized quite sensitive orientations moments, which are essential understand microscopic mechanisms spin-driven emergent phenomena. Here, we present POlarized Triple-Axis spectrometer PONTA Japan Research Reactor 3 (JRR-3), show capabilities unpolarized by introducing recent results instrument.
${\mathrm{ErNi}}_{2}{\mathrm{B}}_{2}\mathrm{C}$ is the first material in which a microscopic coexistence between weak ferromagnetism (WFM) and superconductivity (SC) was confirmed by neutron diffraction technique. In present paper, we report detailed WFM structure its ordering process. phase, but clear peaks appear at $(n/2000)$ with $n=\mathrm{even}.$ The analysis revealed that one from 20 Er magnetic moments contributes to such spins form ferromagnetic sheets periodicity of...
We report neutron scattering results on the spin dynamics in paramagnetic (PM) and ferromagnetic (FM) states of 50% hole-doped manganites ${\mathrm{Pr}}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_{3}$ ${\mathrm{Nd}}_{1/2}{\mathrm{Sr}}_{1/2}{\mathrm{MnO}}_{3}.$ In PM phase, these systems exhibit two kinds diffuse scatterings: an isotropic quasielastic a dynamical ridge-type, i.e., two-dimensional FM scattering. With decreasing temperature, both enter pure metallic state, but state possess strong...
Using inelastic neutron scattering we measured the microscopic magnetic coupling associated with ferromagnetic clusters of ``colossal magnetoresistance'' compound ${\mathrm{Pr}}_{0.70}{\mathrm{Ca}}_{0.30}{\mathrm{MnO}}_{3}$. When insulating-to-metal (I-M) transition is induced by an external field there a discontinuous change in spin-wave stiffness constant. This result implies that I-M not achieved simple percolation micron-sized metallic as currently believed, but involves first-order...
We have observed a magnetic vortex lattice (VL) in BaFe2(As_{0.67}P_{0.33})2 (BFAP) single crystals by small-angle neutron scattering (SANS). With the field along c-axis, nearly isotropic hexagonal VL was formed range from 1 to 16 T, which is record for this technique pnictides, and no symmetry changes were observed. The temperature-dependence of signal measured confirms presence (non d-wave) nodes superconducting gap structure measurements at 5 T below. nodal effects suppressed high fields....
Magnetic excitations in the multiferroic ${\mathrm{Ba}}_{2}{\mathrm{CoGe}}_{2}{\mathrm{O}}_{7}$ are measured by combination of unpolarized and polarized neutron-scattering techniques. The neutron spectrum reveals an anisotropic $\mathbf{Q}$ dependence intensity electromagnon mode at 4 meV. analysis spectra identifies directions magnetic fluctuations observed modes. determined modes consistent with calculation extended spin-wave theory. A couple transverse a single longitudinal involved...
We use neutron scattering to study the spin and charge-orbital ordering (CO-OO) in nearly half-doped perovskite manganite ${\mathrm{Pr}}_{0.55}{({\mathrm{Ca}}_{0.8}{\mathrm{Sr}}_{0.2})}_{0.45}\mathrm{Mn}{\mathrm{O}}_{3}$ (PCSMO). On cooling from room temperature, PCSMO first enters into a CO-OO state below ${T}_{\mathit{CO}}$ then becomes CE-type long-range ordered antiferromagnet ${T}_{N}$. At temperatures above ${T}_{N}$ but $({T}_{N}<T<{T}_{\mathit{CO}})$, spins form highly...
Using small angle neutron scattering, the anisotropy of magnetic vortex lattice (VL), in heavily hole-doped pnictide superconductor ${\text{KFe}}_{2}{\text{As}}_{2}$, was studied. Well-ordered VL scattering patterns were measured with fields applied directions between $\mathbf{B}\ensuremath{\parallel}\mathbf{c}$ and basal plane, rotating either towards $[100]$ or $[110]$. Slightly distorted hexagonal observed when $\mathbf{B}\ensuremath{\parallel}\mathbf{c}$. However, pattern more strongly...
It has been proposed that Sr_2RuO_4 exhibits spin triplet superconductivity mediated by ferromagnetic fluctuations. So far neutron scattering experiments have failed to detect any clear evidence of fluctuations but, instead, this type successful in confirming the existence incommensurate near q=(1/3 1/3 0). For reason there many efforts associate contributions such mechanism its superconductivity. Our unpolarized inelastic measurements revealed these possess c-axis anisotropy with an...
Iron-based superconductors, where the Cooper pairing is theorized to arise from magnetic interactions, have emerged as very good model systems for studies of interplay between superconductivity and magnetism. Superconducting vortices, introduced by an applied field, can serve a sensitive probe superconducting state in host material. The authors used small-angle neutron scattering study vortex lattice KFe${}_{2}$As${}_{2}$, perform comprehensive characterization effects multiband Pauli...
The response of vortex state to the magnetic field in Nb3Sn is probed using muon spin rotation and small-angle neutron scattering. A transformation structure between hexagonal squared lattice observed over a relatively low range 2-3 Tesla. gradual increase penetration depth with increasing provides microscopic evidence for anisotropic (or multi-gapped) s-wave pairing suggested by Raman scattering experiment. This result renders need careful examination on difference electronic properties V3Si.
Flux line lattice (FLL) of a quasi-two-dimensional heavy fermion superconductor CeCoIn 5 in perpendicular field was investigated by small-angle neutron scattering technique. A square FLL observed magnetic fields up to 3 T and at 4 splitting diffraction spots observed, indicating reorganization the toward triangular (rhombic) FLL. The form factor is nearly field-independent T. This sharp contrast conventional superconductors, which rapidly decays with increasing field. behavior factor,...
The nature of the magnetic structure and its ordering process into weak ferromagnetic (WFM) phase ${\text{TbNi}}_{2}{^{11}\text{B}}_{2}\text{C}$ has been carefully investigated by an unpolarized neutron diffraction technique. results show that at low temperature, there appear several spin density wave peaks can be indexed two independent propagation vectors, ${\mathbit{q}}_{1}^{\ensuremath{'}}$ ${\mathbit{q}}_{2}$. Detailed measurements various temperatures further reveal higher order...
Magnetic correlation in ${\mathrm{YBaCo}}_{4}{\mathrm{O}}_{7}$ with kagome and triangular lattices was studied through inelastic-neutron-scattering measurements on a single crystal sample. The broad magnetic excitation observed below 45 meV showed dispersions both within the $c$ plane along axis. wave vector minimum energy of totally different from Bragg point. Our analysis first-moment-sum rule suggests that Co ions form unique three-dimensional network geometrically frustration.
The magnetic diffuse scattering of YBaCo4O7 and LuBaCo4O7 with alternating kagome triangular lattices has been studied through neutron measurements on single-crystal samples. In YBaCo4O7, the line-shape-magnetic-diffuse is observed around transition temperature, which consistent Monte Carlo simulation. LuBaCo4O7, not detected. At low propagation vectors reflections are different between LuBaCo4O7. structural distortion in RBaCo4O7 suggested to play a critical role for properties.