2,476 research outputs found
Resonating-valence-bond structure of Gutzwiller-projected superconducting wave functions
Gutzwiller-projected (GP) wave functions have been widely used for describing
spin-liquid physics in frustrated magnets and in high-temperature
superconductors. Such wave functions are known to represent states of the
resonating-valence-bond (RVB) type. In the present work I discuss the RVB
structure of a GP singlet superconducting state with nodes in the spectrum. The
resulting state for the undoped spin system may be described in terms of the
"path integral" over loop coverings of the lattice, thus extending the known
construction for RVB states. The problem of the topological order in GP states
may be reformulated in terms of the statistical behavior of loops. The simple
example of the projected d-wave state on the square lattice demonstrates that
the statistical behavior of loops is renormalized in a nontrivial manner by the
projection.Comment: 6 pages, 4 figures, some numerical data adde
The anisotropic Heisenberg chain in coexisting transverse and longitudinal magnetic fields
The one-dimensional spin-1/2 model in a mixed transverse and
longitudinal magnetic field is studied. Using the specially developed version
of the mean-field approximation the order-disorder transition induced by the
magnetic field is investigated. The ground state phase diagram is obtained. The
behavior of the model in low transverse field is studied on the base of
conformal field theory. The relevance of our results to the observed phase
transition in the quasi-one-dimensional antiferromagnet is
discussed.Comment: 18 pages, 6 figure
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