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 $x=1/m$ ( $m=\mathrm{integer}$) 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 $\pi$ shift in the orbital order across stripes is identified, analogous to the $\pi$ shift in spin order across stripes in cuprates. At $x=1/4\mathrm{}$ and $1/3$, another nonmagnetic phase with diagonal static charge stripes is stabilized at intermediate values of the $t_{2g}$-spins exchange coupling.