Stripes Induced by Orbital Ordering in Layered Manganites

Spin-charge-orbital ordered structures in doped layered manganites are investigated using an orbital-degenerate double-exchange model tightly coupled to Jahn-Teller distortions. In the ferromagnetic phase, unexpected diagonal stripes at x = 1/m ( m = integer) are observed, as in recent experiments. These stripes are induced by the orbital degree of freedom, which forms a staggered pattern in the background. A π shift in the orbital order across stripes is identified, analogous to the π shift in spin order across stripes in cuprates. At x = 1/4 and 1/3, another nonmagnetic phase with diagonal static charge stripes is stabilized at intermediate values of the t_2g-spins exchange coupling.