1,180 research outputs found
Classical antiferromagnet on a hyperkagome lattice
Motivated by recent experiments on Na_4Ir_3O_8 [Y. Okamoto, M. Nohara, H.
Aruga-Katori, and H. Takagi, arXiv:0705.2821 (unpublished)], we study the
classical antiferromagnet on a frustrated three-dimensional lattice obtained by
selectively removing one of four sites in each tetrahedron of the pyrochlore
lattice. This ``hyperkagome'' lattice consists of corner-sharing triangles. We
present the results of large-N mean field theory and Monte Carlo computations
on O(N) classical spin models. It is found that the classical ground states are
highly degenerate. Nonetheless a nematic order emerges at low temperatures in
the Heisenberg model (N=3) via ``order by disorder'', representing the
dominance of coplanar spin configurations. Implications for ongoing experiments
are discussed.Comment: 4 pages, 6 figures, published versio
Critical Current of the Spin-Triplet Superconducting Phase in SrRuO
There have been two different proposals for the spin-triplet order parameter
of the superconducting phase in SrRuO; an -wave order parameter and
the multigap model where some of the bands have the line node. In an effort to
propose an experiment that can distinguish two cases, we study the behavior of
the supercurrent and compute the critical current for these order parameters
when the sample is a thin film with the thickness where is
the coherence length. It is found that the supercurrent behaves very
differently in two models. This will serve as a sharp test for the
identification of the correct order parameter.Comment: 4 pages, 1 figur
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