94 research outputs found
Incoherent non-Fermi liquid scattering in a Kondo lattice
One of the most notorious non-Fermi liquid properties of both archetypal
heavy-fermion systems [1-4] and the high-Tc copper oxide superconductors [5] is
an electrical resistivity that evolves linearly with temperature, T. In the
heavy-fermion superconductor CeCoIn5 [5], this linear behaviour was one of the
first indications of the presence of a zero-temperature instability, or quantum
critical point. Here, we report the observation of a unique control parameter
of T-linear scattering in CeCoIn5, found through systematic chemical
substitutions of both magnetic and non-magnetic rare-earth, R, ions into the Ce
sub-lattice. We find that the evolution of inelastic scattering in Ce1-xRxCoIn5
is strongly dependent on the f-electron configuration of the R ion, whereas two
other key properties -- Cooper-pair breaking and Kondo-lattice coherence -- are
not. Thus, T-linear resistivity in CeCoIn5 is intimately related to the nature
of incoherent scattering centers in the Kondo lattice, which provides insight
into the anomalous scattering rate synonymous with quantum criticality [7].Comment: 4 pages, 3 figures (published version
Magnetic structures and reorientation transitions in noncentrosymmetric uniaxial antiferromagnets
A phenomenological theory of magnetic states in noncentrosymmetric tetragonal
antiferromagnets is developed, which has to include homogeneous and
inhomogeneous terms (Lifshitz-invariants) derived from Dzyaloshinskii-Moriya
couplings. Magnetic properties of this class of antiferromagnets with low
crystal symmetry are discussed in relation to its first known members, the
recently detected compounds Ba2CuGe2O7 and K2V3O8. Crystallographic symmetry
and magnetic ordering in these systems allow the simultaneous occurrence of
chiral inhomogeneous magnetic structures and weak ferromagnetism. New types of
incommensurate magnetic structures are possible, namely, chiral helices with
rotation of staggered magnetization and oscillations of the total
magnetization. Field-induced reorientation transitions into modulated states
have been studied and corresponding phase diagrams are constructed. Structures
of magnetic defects (domain-walls and vortices) are discussed. In particular,
vortices, i.e. localized non-singular line defects, are stabilized by the
inhomogeneous Dzyaloshinskii-Moriya interactions in uniaxial noncentrosymmetric
antiferromagnets.Comment: 18 pages RevTeX4, 13 figure
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