294 research outputs found
Spin-flux phase in the Kondo lattice model with classical localized spins
We provide numerical evidence that a spin-flux phase exists as a ground state
of the Kondo lattice model with classical local spins on a square lattice. This
state manifests itself as a double-Q magnetic order in the classical spins with
spin density at both and and further exhibits fermionic
spin currents around an elementary plaquette of the square lattice. We examine
the spin-wave spectrum of this phase. We further discus an extension to a face
centered cubic (FCC) lattice where a spin-flux phase may also exist. On the FCC
lattice the spin-flux phase manifests itself as a triple-Q magnetically ordered
state and may exist in -Mn alloys.Comment: 5 pages, 3 figure
Broken Time Reversal Symmetry and Superconducting States in the Cuprates
Recently, Kaminski et al. have reported that time reversal symmetry is broken
in the pseudogap phase in the high temperature superconducting material
Bi_2Sr_2CaCu_2O_{2+\delta} (Bi-2212). Here we examine the role of
translationally invariant broken time reversal states on d_{x^2-y^2}
superconductors. In particular, we determine the change in the superconducting
order parameter structure. We find that the broken time reversal pseudogap
state that is consistent with the experiment of Kaminski et al., gives rise to
a novel mixed singlet-triplet pairing d+ip phase. This d+ip state is shown to
give rise to a helical superconducting phase. Consequences of this d+ip state
on Josephson experiments are discussed.Comment: 5 pages, 1 figur
Kondo effect in the presence of spin-orbit coupling
We study the T=0 Kondo physics of a spin-1/2 impurity in a
non-centrosymmetric metal with spin-orbit interaction. Within a simple
variational approach we compute ground state properties of the system for an
{\it arbitrary} form of spin-orbit coupling consistent with the crystal
symmetry. This coupling produces an unscreened impurity magnetic moment and can
lead to a significant change of the Kondo energy. We discuss implications of
this finding both for dilute impurities and for heavy-fermion materials without
inversion symmetry.Comment: TeXLive (Unix), revtex4-1, 5 page
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