254 research outputs found
Observation of Modulated Quadrupolar Structures in PrPb3
Neutron diffraction measurements have been performed on the cubic compound
PrPb3 in a [001] magnetic field to examine the quadrupolar ordering.
Antiferromagnetic components with q=(1/2+-d 1/2 0), (1/2 1/2+-d 0) (d~1/8) are
observed below the transition temperature TQ (0.4 K at H=0) whose amplitudes
vary linear with H and vanish at zero field, providing the first evidence for a
modulated quadrupolar phase. For H<1 T, a non-square modulated state persists
even below 100 mK suggesting quadrupole moments associated with a Gamma3
doublet ground state to be partially quenched by hybridization with conduction
electrons.Comment: Physical Review Letters, in press. 4 pages, 4 figure
Antiferro-quadrupole state of orbital-degenerate Kondo lattice model with f^2 configuration
To clarify a key role of orbitals in the emergence of
antiferro-quadrupole structure in PrPb, we investigate the ground-state
property of an orbital-degenerate Kondo lattice model by numerical
diagonalization techniques. In PrPb, Pr has a
configuration and the crystalline-electric-field ground state is a non-Kramers
doublet . In a - coupling scheme, the state is
described by two local singlets, each of which consists of two electrons
with one in and another in orbitals. Since in a cubic
structure, has localized nature, while orbitals are
rather itinerant, we propose the orbital-degenerate Kondo lattice model for an
effective Hamiltonian of PrPb. We show that an antiferro-orbital state is
favored by the so-called double-exchange mechanism which is characteristic of
multi-orbital systems.Comment: 3 pages, 3 figures, Proceedings of Skutterudite2007 (September 26-30,
2007, Kobe
Superconductivity in the Ferroquadrupolar State in the Quadrupolar Kondo Lattice PrTiAl
The cubic compound PrTiAl is a quadrupolar Kondo lattice system
that exhibits quadrupolar ordering due to the non-Kramers ground
doublet and has strong hybridization between and conduction electrons. Our
study using high-purity single crystal reveals that PrTiAl exhibits
type-II superconductivity at mK in the nonmagnetic
ferroquadrupolar state. The superconducting critical temperature and field
phase diagram suggests moderately enhanced effective mass of
Ferromagnetic Transition in a Caged Compound NdOs2Zn20
AbstractMagnetic properties in a caged compound NdOs2Zn20 have been studied by the measurements of magnetization M, magnetic susceptibility M/B, and specific heat C. The measurements indicate that NdOs2Zn20 shows a structural transition at Ts = 62K and a ferromagnetic transition at TC = 0.6K. The structural transition is also observed in the La counter-part LaOs2Zn20 at Ts = 151K. The results of M (T)/B, M (B), and C(T) of NdOs2Zn20 are reproduced by a crystalline electrical field scheme with a Kramers doublet ground state
Highly anisotropic strain dependencies in PrIrZn
We report thermal expansion and magnetostriction of the cubic non-Kramers
system PrIrZn with a non-magnetic ground state
doublet. In previous experiments, antiferroquadrupolar order at
\hbox{\,K} and a Fermi liquid state around
\,T for \hbox{},
indicative of possible ferrohastatic order, were discovered. For magnetic
fields \hbox{}, the low temperature longitudinal
and transverse thermal expansion and magnetostriction are highly anisotropic.
The resulting volume strain is very small, indicating that the Pr valence
remains nearly constant as a function of magnetic field. We conclude that the
Fermi liquid state around forms through a very little change
in c-f hybridization. This result is in sharp contrast to Ce- and Yb-based
Kramers Kondo lattices which show significantly larger volume strains due to
the high sensitivity of the Kondo temperature to hydrostatic pressure.Comment: 8 pages, 8 figure
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