Researchers have discovered a new family of stable quasicrystals made from only two elements, a rare earth and cadmium. The family includes the first magnetic binary quasicrystals. Quasicrystals are metallic alloys that lack the periodic order seen in conventional crystals. Instead, they exhibit aperiodic, long-range order and have “forbidden” rotational symmetries (for example, five-fold). Most are made from three or four elements. Binary quasicrystals are rare and sought by scientists because they offer a cleaner way to investigate the relationships between the unusual structures of quasicrystals and their properties. For this family, there also are crystalline approximants — materials that are periodic but with atomic decorations similar to those of quasicrystals — that are close in composition allowing comparisons with related crystalline materials. The Department of Energy’s Advanced Photon Source was used to confirm their structure. The discovery of this family enables researchers to study the nature of magnetic interactions in quasicrystals. Thus far, studies show the magnetic behavior of these quasicrystals and related approximants is vastly different.
A Family of Binary Magnetic Icosahedral Quasicrystals Based on Rare Earths and Cadmium