ABSTRACT
We show results on the vortex core dissipation through current-voltage measurements under applied pressure and magnetic field in the superconducting phase of CeCoIn{5}. We find that as soon as the system becomes superconducting, the vortex core resistivity increases sharply as the temperature and magnetic field decrease. The sharp increase in flux-flow resistivity is due to quasiparticle scattering on critical antiferromagnetic fluctuations. The strength of magnetic fluctuations below the superconducting transition suggests that magnetism is complementary to superconductivity and therefore must be considered in order to fully account for the low-temperature properties of CeCoIn{5}.
ABSTRACT
X-ray diffraction, electrical resistivity, magnetic susceptibility, and specific heat measurements on Ce(1-x)Yb(x)CoIn5 (0≤x≤1) reveal that many of the characteristic features of the x=0 correlated electron state are stable for x≤0.775 and that phase separation occurs for x>0.775. The stability of the correlated electron state is apparently due to cooperative behavior of the Ce and Yb ions, involving their unstable valences. Low-temperature non-Fermi liquid behavior is observed and varies with x, even though there is no readily identifiable quantum critical point. The superconducting critical temperature T(c) decreases linearly with x towards 0 K as xâ1, in contrast with other HF superconductors where T(c) scales with T(coh).
ABSTRACT
A series of high-pressure electrical resistivity measurements on single crystals of TbTe3 reveal a complex phase diagram involving the interplay of superconducting, antiferromagnetic and charge-density-wave order. The onset of superconductivity reaches a maximum of almost 4 K (onset) near approximately 12.4 GPa.
ABSTRACT
The evolution of the Fermi surface of CeRh(1-x)CoxIn5 was studied as a function of Co concentration x via measurements of the de Haas-van Alphen effect. By measuring the angular dependence of quantum oscillation frequencies, we identify a Fermi-surface sheet with f-electron character which undergoes an abrupt change in topology as x is varied. Surprisingly, this reconstruction does not occur at the quantum critical concentration x(c), where antiferromagnetism is suppressed to T=0. Instead we establish that this sudden change occurs well below x(c), at the concentration x approximately 0.4, where long-range magnetic order alters its character and superconductivity appears. Across all concentrations, the cyclotron effective mass of this sheet does not diverge, suggesting that critical behavior is not exhibited equally on all parts of the Fermi surface.
ABSTRACT
The filled skutterudite compound PrOs4P12 was synthesized in single-crystal form using a molten metal flux growth technique. Low-temperature magnetization, specific heat, and electrical resistivity measurements showed no indication of a phase transition down to 0.1 K but had features indicative of crystalline electric field (CEF) effects. Analyses of these features in terms of a cubic CEF suggest a Γ1 singlet or a Γ3 doublet ground state separated by 30-50 K from a Γ5 triplet first excited state.
ABSTRACT
Electrical resistivity, specific heat, and magnetization measurements to temperatures as low as 80 mK and magnetic fields up to 16 T were made on the filled skutterudite compound PrOs4As12. The measurements reveal the presence of two ordered phases at temperatures below approximately 2.3 K and in fields below approximately 3 T. Neutron-scattering experiments in zero field establish an antiferromagnetic ground state < 2.28 K. In the antiferromagnetically ordered state, the electronic-specific heat coefficient gamma approximately 1 J/mol x K2 below 1.6 K and 0 < or = H < or = 1.25 T. The temperature and magnetic-field dependence of the electrical resistivity and specific heat in the paramagnetic state are consistent with single-ion Kondo behavior with a low Kondo temperature on the order of 1 K. The electronic-specific heat in the paramagnetic state can be described by the resonance-level model with a large zero-temperature electronic-specific heat coefficient that decreases with increasing magnetic field from approximately 1 J/mol x K2 at 3 T to approximately 0.2 J/mol x K2 at 16 T.
ABSTRACT
We report on a comprehensive optical, transport, and thermodynamic study of the Zintl compound Yb(14)MnSb(11), demonstrating that it is the first ferromagnetic Kondo lattice compound in the underscreened limit. We propose a scenario whereby the combination of Kondo and Jahn-Teller effects provides a consistent explanation of both transport and optical data.
