Ichihiro Yamauchi

Cooperative Order in the Weakly Magnetic Domain of LaFeAsO1−xFx near the Doping Phase Boundary

Spatial phase separation into mesoscopic domains of non-magnetic [superconducting (SC) below Tc \( \simeq \) 25.5 K] and two kinds of magnetic phases, one showing disordered spin density wave (d-SDW) order and another associated with glassy weak magnetism (WM), are observed below ∼100 K by muon spin rotation (μSR) in LaFeAsO1−xFx for x = 0.057(3), which is near the boundary of these phases on the doping phase diagram. In contrast to the competing order observed in the regular SDW phase of Ba(Fe1−xCox)2As2, the WM domain exhibits cooperative coupling of superconducting and magnetic order parameters as inferred from strong diamagnetism and the associated negative shift of μSR frequency just below Tc.

7Li and 51V NMR studies on local symmetry and charge disproportionation in quasi-one-dimensional conductor β-Li0.33V2O5

We have made 7Li and 51V NMR measurements on a single crystal to investigate the local symmetry and the charge disproportionation in the metallic phase of the quasi-one-dimensional conductor β-Li0.33V2O5. The electric quadrupole tensors at the Li sites are determined and the Li ordering is discussed on the basis of the recent X-ray diffraction results. We also report the temperature dependence of the 51V Knight shift and the 51V nuclear spin-lattice relaxation rate, indicating the presence of the charge disproportionation even in the metallic phase.

Quest for the Origin of Heavy Fermion Behavior in d-Electron Systems

Spin fluctuation is presumed to be one of the key properties in understanding the microscopic origin of heavy-fermion-like behavior in the class of transition-metal compounds, including LiV2O4, Y(Sc)Mn2, and YMn2Zn20. In this review, we demonstrate by our recent study of muon spin rotation/relaxation that the temperature (T) dependence of the longitudinal spin relaxation rate (λ ≡ 1/T1) in these compounds exhibits a common trend of leveling off to a constant value (λ ∼ const.) below a characteristic temperature, T*. This is in marked contrast to the behavior predicted for normal metals from the Korringa relation, λ ∝ T/ν, where the spin fluctuation rate (ν) in the Pauli paramagnetic state is given as a constant, \(\nu \simeq 1\)/[hD(EF)] [with D(EF) being the density of states at the Fermi energy]. Thus, the observed behavior of λ implies that the spin fluctuation rate becomes linearly dependent on temperature, ν ∝ T, suggesting that heavy quasiparticles develop in a manner satisfying D(EF) ∝ (m*)σ ∝ 1/T ...

Structural anomalies and short-range magnetic correlations in the orbitally degenerate systemSr2VO4

We report on the electronic ground state of a layered perovskite vanadium oxide

Spin diffusion in the quasi-one-dimensional conductor β-Na0.33V2O5

{\mathrm{Sr}}_{2}{\mathrm{VO}}_{4}

Local spin susceptibility in the metallic phase of the quasi-one-dimensional conductor β-Li0.33V2O5

studied by the combined use of synchrotron radiation x-ray diffraction (SR-XRD) and muon spin rotation/relaxation

Spin Dynamics in Quasi-One-Dimensional Conductor β-Na0.33V2O5: 51V Nuclear Spin–Lattice Relaxation Measurements

(\ensuremath{\mu}\mathrm{SR})

NMR Study of the Metal‐Insulator Transition in β‐Na0.33V2O5

techniques, where

Bipartite magnetic parent phases in the iron oxypnictide superconductor

\ensuremath{\mu}\mathrm{SR}

Local magnetic susceptibility and electronic structure of the quasi-one-dimensional conductor β − Na 0.33 V 2 O 5 : V 51 NMR study in a single crystal

measurements were extended down to 30 mK. We found an intermediate orthorhombic phase between