Brookhaven National Laboratory
Disappearing stripes linked with free electron movement: Scientists used a precision microscope to simultaneously explore electrons' arrangements and movements as charge carriers called holes were added to transform a copper-oxide material from an insulator to a superconductor. With increasing hole density, the material first takes on a mysterious "pseudogap" phase that overlaps and competes with superconductivity. Region I: While still in the pseudogap phase, some electrons occupy static positions apparent as a striped pattern (top inset) while other electrons are free to move and carry current, but only in certain directions (arcs with gaps in lower inset). Region II: At a critical point of hole density, the static stripes disappear and all electrons can move freely in all directions. The point of maximal superconductivity (Max Tc) lies within this region. Finding ways to prevent the static electron arrangement may be one way to push the Max Tc to a higher temperature more suitable for real-world applications.