Iron-rich lamellae in a semiconductor

phys.org | 12/10/2018 | Staff
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There is often a pronounced symmetry when you look at the lattice of crystals: It doesn't matter where you look—the atoms are uniformly arranged in every direction. This behavior would also be expected of a crystal, which physicists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the University of Warsaw and the Polish Academy of Sciences produced with a compound from an indium arsenide semiconductor spiked with iron. The material, however, did not adhere to perfect symmetry. The iron formed two-dimensional, lamellar-shaped structures in the crystal that were magnetic. In the long term, the result could be vital in understanding superconductors.

"Using the possibilities of our Ion Beam Center, we fired fast iron ions at a crystal made of indium arsenide, a semiconductor made of indium and arsenic," says Dr. Shengqiang Zhou, physicist at the HZDR Institute of Ion Beam Physics and Materials Research. "The iron penetrated approximately 100 nanometers deep into the crystal surface." The iron ions were in the minority, constituting only a few percent in the surface. The researchers then fired light pulses at the crystal using a laser. The flashes were ultra-short so that only the surface melted. "For much less than a microsecond, the top one hundred nanometers were a hot soup, whereas the crystal underneath remained cold and well ordered," Zhou says, describing the result.

Surface - Blink - Eye - Laser - Bombardment

The crystal surface cooled again just a blink of an eye after the laser bombardment. Something unusual happened: The surface had essentially reverted back to the indium arsenide lattice structure. The cooling, however, was so rapid that the iron atoms did not have sufficient time to find and occupy a regular lattice state...
(Excerpt) Read more at: phys.org
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