Scientists discover super crystals in semiconductor

Certain semi-conducting solids host super crystals - crystals, which are hundreds to thousand times larger than conventional crystals, scientists from the University of Arizona have found.

Washington, Aug 17 : Certain semi-conducting solids host 'super crystals' - crystals, which are hundreds to thousand times larger than conventional crystals, scientists from the University of Arizona have found.

Super crystals are unique in the sense that not only do they display a repeating pattern of atoms or molecules, they also show a periodically repeating super-structure of plane traps for electrons.

"The distance between these plane traps, which are called soliton walls, are typically hundreds to thousands times greater than the distances between the organic molecules," said UA physicist Andrei Lebed.

Lebed, who collaborated with graduate student Si Wu, said pure super-crystalline organic semiconductors conduct electricity much differently than conventional solids.

Super-crystalline semiconductors, for example, could create splashes of current on electrical contacts, even in a uniform electric field, he said.

He said they are also among the first solid-state theorists to collaborate with experimentalists in studying other materials that might possibly be super-crystalline.

"Our hopes for a discovery of a long awaited super-crystalline phase were raised after we started to analyze experimental data of James Brooks' group. Unfortunately, so far no one has discovered super crystals in organic metals," Lebed said.

"When Wu and I, who are theorists, analyzed the experimental data, what we found was a complete surprise to us. Our theoretical calculations showed that the only way to explain the appearance of a mysterious high magnetic field state was to suggest that it appears inside a super-crystalline phase," he said.

He, however, said future experiments are needed to confirm the theoretical discovery.

Lebed and Wu published their study in the July 13 issue of Physical Review Letters.

ANI