1,076 research outputs found
Crystal-field effects in the mixed-valence compounds Yb2M3Ga9 (M= Rh, Ir)
Magnetic susceptibility, heat capacity, and electrical resistivity
measurements have been carried out on single crystals of the intermediate
valence compounds Yb2Rh3Ga9 and Yb2Ir3Ga9. These measurements reveal a large
anisotropy due apparently to an interplay between crystalline electric field
(CEF) and Kondo effects. The temperature dependence of magnetic susceptibility
can be modelled using the Anderson impurity model including CEF within an
approach based on the Non-Crossing Approximation.Comment: Accepted to Phys. Rev.
Intermetallic compounds in heterogeneous catalysis - a quickly developing field
The application of intermetallic compounds for understanding in heterogeneous catalysis developed in an excellent way during the last decade. This review provides an overview of concepts and developments revealing the potential of intermetallic compounds in fundamental as well as applied catalysis research. Intermetallic compounds may be considered as platform materials to address current and future catalytic challenges, e.g. in respect to the energy transition
Unconventional magnetism in multivalent charge-ordered YbPtGe probed by Pt- and Yb-NMR
Detailed Pt- and Yb nuclear magnetic resonance (NMR) studies
on the heterogeneous mixed valence system YbPtGe are reported. The
temperature dependence of the Pt-NMR shift indicates the
opening of an unusual magnetic gap below 200\,K. was analyzed by a
thermal activation model which yields an isotropic gap \,K. In contrast, the spin-lattice relaxation rate () does
not provide evidence for the gap. Therefore, an intermediate-valence picture is
proposed while a Kondo-insulator scenario can be excluded. Moreover,
() follows a simple metallic behavior, similar to the reference
compound YPtGe. A well resolved NMR line with small shift is assigned to
divalent Yb. This finding supports the proposed model with two sub-sets
of Yb species (di- and trivalent) located on the Yb2 and Yb1 site of the
YbPtGe lattice.Comment: Submitted in Physical Review B (Rapid Communication
Separable Structure of Many-Body Ground-State Wave Function
We have investigated a general structure of the ground-state wave function
for the Schr\"odinger equation for identical interacting particles (bosons
or fermions) confined in a harmonic anisotropic trap in the limit of large .
It is shown that the ground-state wave function can be written in a separable
form. As an example of its applications, this form is used to obtain the
ground-state wave function describing collective dynamics for trapped
bosons interacting via contact forces.Comment: J. Phys. B: At. Mol. Opt. Phys. 33 (2000) (accepted for publication
On the origin of heavy quasiparticles in LiV_2O_4
An explanation is provided for the heavy quasiparticle excitations in
LiV_2O_4. It differs considerably from that of other known heavy-fermion
systems. Main ingredients of our theory are the cubic spinel structure of the
material and strong short-range correlations of the d electrons. The large
gamma-coefficient is shown to result from excitations of Heisenberg spin 1/2
rings and chains. The required coupling constant is calculated from LDA+U
calculations and is found to be of the right size. Also the calculated
Sommerfeld-Wilson ratio is reasonably close to the observed one.Comment: REVTEX, 5 pages, 2 figure
Inertial parameters and superfluid-to-normal phase transition in superdeformed bands
The quasiclassically exact solution for the second inertial parameter is found in self-consistent way. It is shown that superdeformation and
nonuniform pairing arising from the rotation induced pair density significantly
reduce this inertial parameter. The different limiting cases for ,
which allow to study an interplay between rapid rotation, pairing correlations,
and mean field deformation, are considered. The new signature for the
transition from pairing to normal phase is suggested in terms of the variation
of versus spin. Experimental data indicate the existence of
such transition in the three superdeformed mass regions.Comment: 8 pages, LaTeX, 3 figure
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