Breakdown of fourfold symmetry of Fermi surface and magnetic excitation spectrum Original Research Article

Performing the slave-boson mean-field approximation to the two-dimensional t–J model under the assumption of the uniform charge density, we find two mechanisms that lead to the breaking of fourfold symmetry of the Fermi surface (FS) and the magnetic excitation spectrum. One mechanism originates from the J-term, which has an intrinsic instability toward the formation of a quasi-one-dimensional FS. The other mechanism comes from the inclusion of the small interlayer hopping t⊥, which can lead to the drastic breaking of fourfold symmetry in the diagonal incommensurate magnetic peaks around (π, π). These findings are discussed with emphasis on possible relevance to La2−xSrxCuO4 systems.