54 research outputs found
Strong Correlation between Anomalous Quasiparticle Scattering and Unconventional Superconductivity in Hidden Order Phase of URuSi
The pressure dependent electrical resistivity of URuSi has been
studied at high pressure across the first order phase boundary of where
the ground state switches under pressure from "hidden order" (HO) to large
moment antiferromagnetic (LAFM) states. The electrical transport in
URuSi at low temperatures shows a strong sample dependence. We have
measured an ultra-clean single crystal whose quality is the highest among those
used in previous studies. The generalized power law
analysis finds that the electric
transport property deviates from Fermi liquid theory in the HO phase but obeys
the theory well above . The analysis using the polynomial in
expression
reveals the relation in the HO
phase. While the pressure dependence of is very weak,
is roughly proportional to . This suggests a strong
correlation between the anomalous quasiparticle scattering and the
superconductivity and that both have a common origin. The present study
clarifies a universality of the HO phase inherent in strongly correlated
electron superconductors near quantum criticality
Enhancing the Superconducting Transition Temperature due to Strong-Coupling Effect under Antiferromagnetic Spin Fluctuations in CeRh1-xIrxIn5 : 115In-NQR Study
We report on systematic evolutions of antiferromagnetic (AFM) spin
fluctuations and unconventional superconductivity (SC) in heavy-fermion (HF)
compounds CeRhIrIn via In
nuclear-quadrupole-resonance (NQR) experiment. The measurements of nuclear
spin-lattice relaxation rate have revealed the marked development of
AFM spin fluctuations as a consequence of approaching an AFM ordered state with
increasing Rh content. Concomitantly the superconducting transition temperature
and the energy gap increase drastically from K and in CeIrIn up to K and in
CeRhIrIn, respectively. The present work suggests that the
AFM spin fluctuations in close proximity to the AFM quantum critical point are
indeed responsible for the onset of strong-coupling unconventional SC with the
line node in the gap function in HF compounds.Comment: 4pages,5figures,to appear in Phys. Rev. Let
Optical Conductivity Study of f Electron States in YbCu2Ge2 at High Pressures to 20 GPa
Optical conductivity [σ(ω)] of YbCu2Ge2 has been measured at external pressures (P) to 20 GPa, to study the P evolution of f electron hybridized states. At P=0, σ(ω) shows a marked mid-infrared (mIR) peak at 0.37 eV, which is due to optical excitations from f14 (Yb2+) state located below the Fermi level. With increasing P, the mIR peak shows significant shifts to lower energy, reaching 0.18 eV at P=20 GPa. This result indicates that the f14 energy level increases toward the Fermi level with P. Such a shift of the f electron level with P has been expected from theoretical considerations, but had never been demonstrated by spectroscopic experiment under high P. The obtained results are also analyzed in terms of the P evolution of the conduction-f electron hybridization
Helicity Selection of the Cycloidal Order in Noncentrosymmetric EuIrGe
The magnetic helicities of the cycloidal ordering in EuIrGe, with a
noncentrosymmetric tetragonal structure, have been studied by circularly
polarized resonant X-ray diffraction. It is shown that the helicity of each
cycloidal domain is uniquely determined and satisfies the symmetry relations of
the point group of the crystal structure. The result shows that the
cycloidal helicity is determined by the Dzyaloshinskii-Moriya type
antisymmetric exchange interaction. The domain selection and the phase
transition by the external magnetic field along [100] and [110] have also been
studied. It is shown that the cycloidal plane prefers to be perpendicular to
the field and the transverse conical state is realized.Comment: 6 pages, 4 figures, 5 figures in the supplemental material, accepted
for publication in J. Phys. Soc. Jp
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