Spin-triplet f-wave pairing due to three-site cyclic-exchange ferromagnetic interactions

Abstract

Ferromagnetiam and superconductivity in a two-dimensional triangular-lattice Hubbard model are studied using the density-matrix renormalization group method. We propose a mechanism of the {\it f}-wave spin-triplet pairing derived from the three-site cyclic-exchange ferromagnetic interactions. We point out that a triangular network of hopping integrals, which is required for the three-site cyclic hopping processes, is contained in the (possibly) spin-triplet superconducting systems, such as Bechgaard salts (TMTSF)${}_2$X, cobalt oxide Na${}_{0.35}$CoO${}_2$$\cdot$1.3H${}_2$O, and layered perovskite Sr${}_2$RuO${}_4$.

4 pages, 4 figures