32 research outputs found
Exotic Heavy Fermion State in the Filled Skutterudite PrFeP Uncovered by the de Haas-van Alphen Effect
We report the de Haas-van Alphen (dHvA) experiment on the filled skutterudite
PrFeP exhibiting apparent Kondo-like behaviors in the transport and
thermal properties. We have found enormously enhanced cyclotron effective mass
in the high field phase (HFP), which
indicates that PrFeP is the first Pr-compound in which really heavy
mass has been unambiguously confirmed. Also in the low field non-magnetic
ordered phase (LOP), we observed the dHvA branch with that is quite heavy taking into account its small Fermi surface volume
(0.15% of the Brillouin zone size). The insensitivity of mass in LOP against
the magnetic field suggests that the quadrupolar interaction plays a main role
both in the mass renormalization and the LOP formation.Comment: 5 pages, 5 figures, Phys. Rev. B (01 October 2002) in pres
Optical Properties of MFe_4P_12 filled skutterudites
Infrared reflectance spectroscopy measurements were made on four members of
the MFe_4P_12 family of filled skutterudites, with M=La, Th, Ce and U. In
progressing from M=La to U the system undergoes a metal-insulator transition.
It is shown that, although the filling atom induces such dramatic changes in
the transport properties of the system, it has only a small effect on lattice
dynamics. We discuss this property of the compounds in the context of their
possible thermoelectric applications.Comment: Manuscript in ReVTeX format, 7 figures in PostScirpt forma
Muon-spin rotation and magnetization studies of chemical and hydrostatic pressure effects in EuFe_{2}(As_{1-x}P_{x})_{2}
The magnetic phase diagram of EuFe(AsP) was
investigated by means of magnetization and muon-spin rotation studies as a
function of chemical (isovalent substitution of As by P) and hydrostatic
pressure. The magnetic phase diagrams of the magnetic ordering of the Eu and Fe
spins with respect to P content and hydrostatic pressure are determined and
discussed. The present investigations reveal that the magnetic coupling between
the Eu and the Fe sublattices strongly depends on chemical and hydrostatic
pressure. It is found that chemical and hydrostatic pressure have a similar
effect on the Eu and Fe magnetic order.Comment: 11 pages, 10 figure
Anomalous heavy-fermion and ordered states in the filled skutterudite PrFe4P12
Specific heat and magnetization measurements have been performed on
high-quality single crystals of filled-skutterudite PrFe_4P_{12} in order to
study the high-field heavy-fermion state (HFS) and low-field ordered state
(ODS). From a broad hump observed in C/T vs T in HFS for magnetic fields
applied along the direction, the Kondo temperature of ~ 9 K and the
existence of ferromagnetic Pr-Pr interactions are deduced. The {141}-Pr nuclear
Schottky contribution, which works as a highly-sensitive on-site probe for the
Pr magnetic moment, sets an upper bound for the ordered moment as ~ 0.03
\mu_B/Pr-ion. This fact strongly indicates that the primary order parameter in
the ODS is nonmagnetic and most probably of quadrupolar origin, combined with
other experimental facts. Significantly suppressed heavy-fermion behavior in
the ODS suggests a possibility that the quadrupolar degrees of freedom is
essential for the heavy quasiparticle band formation in the HFS. Possible
crystalline-electric-field level schemes estimated from the anisotropy in the
magnetization are consistent with this conjecture.Comment: 7 pages and 7 figures. Accepted for publication in Phys. Rev.
Evidence for unconventional superconductivity in single crystals of the antiferromagnetic heavy-electron compound URu2Si2
Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials
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MAGNETORESISTANCE MEASUREMENT IN URANIUM COPPER (4+X) ALUMINUM(8-X)
Low temperature properties of Yb1.2-xEuxMo6S 8 under pressure
The properties of Yb1.2-xEuxMo6S 8 compounds have been investigated by means of electrical resistivity and ac magnetic susceptibility measurements under hydrostatic pressure up to 20 kbar and quasi-hydrostatic pressure up to 100 kbar. A temperature-pressure-Eu concentration phase diagram showing the crystallographic, normal and superconducting phases of these compounds was constructed.Les propriétés des composés pseudoternaires Yb1.2-xEux Mo6S8 ont été étudiées à l'aide des mesures de résistivité électrique et de susceptibility magnétique ac sous pression hydrostatique jusqu'à 20 kbar et quasi hydrostatique jusqu'à 100 kbar. Un diagramme de phase de température-pression-concentration d'Eu montrant les phases cristallographiques, normales et superconductrices de ces composés a été construit
Magnetoelastic contribution to the elastic constants of terbium, dysprosium and erbium
On a mesuré la variation de vitesse des ondes élastiques longitudinales et de cisaillement dans des monocristaux de Tb, Dy et Er en fonction de l'aimantation et de la température. Un champ magnétique de 75 kOe était utilisé dans la gamme de température 4,2-300 K laquelle comprenait toutes les phases ordonnées des matériaux. Pour rendre compte des phénomènes observés, on a vérifié qualitativement que l'interaction magnétoélastique doit être considérée jusqu'au 2e ordre pour les contraintes, et que l'énergie élastique de 3e ordre ne peut pas être négligée.We have measured the dependence of the longitudinal and shear elastic waves velocity of Tb, Dy and Er single-crystals on magnetization and temperature. Data were taken in magnetic fields up to 75 kOe, in the temperature range of 4.2-300 K, which included all the ordered phases of these materials. We found qualitatively that to explain the observed behavior, the magnetoelastic interaction have to be treated up to 2nd order in the strains and that the 3rd order elastic energy can not be neglected