Figure 2.

Stripe and grid configurations of holes (circles) in an antiferromagnetic background (arrows, indicating spin direction) at the same hole concentration level (d denotes the distance between stripe or grid lines). Note the change in sign of the local magnetization in the magnetic domains (π phase shift), which makes motion of the holes across line segments energetically inexpensive. Both configurations correspond to low energy states, with a large activation energy for a transition between them, caused by the Coulomb repulsion between holes.