New physics in a copper-iridium compound

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Posted on August 9, 2013
(a) Cu-Ir chain of Sr3CuIrO6. Oxygen atoms surround both copper (Cu2+) and iridium (Ir4+) cations (ions positively charged due to the loss of electrons to the oxygen atoms, which become negatively-charged anions). The copper cation forms a planar arrangement with the surrounding oxygen anions, while the iridium cation resides at the center of an octahedral arrangement of oxygen anions. (b) Magnon dispersion obtained from experiment (solid squares) and theory (lines). (c) Unusual antiferromagnetic (AF) and ferromagnetic (FM) exchange mix between Cu and Ir. They cooperate because SOC anti-parallelizes the 5dxy and 5dxz/5dyz spins on the Ir ion. The latter is also effectively prohibited from flipping due to quantum inference, leading to the easy-z-axis exchange anisotropy.

(a) Cu-Ir chain of Sr3CuIrO6. Oxygen atoms surround both copper (Cu2+) and iridium (Ir4+) cations (ions positively charged due to the loss of electrons to the oxygen atoms, which become negatively-charged anions). The copper cation forms a planar arrangement with the surrounding oxygen anions, while the iridium cation resides at the center of an octahedral arrangement of oxygen anions. (b) Magnon dispersion obtained from experiment (solid squares) and theory (lines). (c) Unusual antiferromagnetic (AF) and ferromagnetic (FM) exchange mix between Cu and Ir. They cooperate because SOC anti-parallelizes the 5dxy and 5dxz/5dyz spins on the Ir ion. The latter is also effectively prohibited from flipping due to quantum inference, leading to the easy-z-axis exchange anisotropy.

An unexpected magnetic behavior within Sr3CuIrO6, a transition-metal compound (TMC) that combines the transition metal copper with the transition metal iridium has been revealed by research at the U.S. Department of Energy Office of Science’s Advanced Photon Source (APS). These results indicate that mixing certain transition metal systems can yield TMCs with surprising physical properties unattainable with these systems alone, and may eventually lead to new materials for applications such as electronic memory devices and quantum computation.

The researchers in this study, published in Physical Review Letters, relied on theoretical calculations complimented by x-ray measurements performed at the X-ray Science Division 9-ID x-ray beamline at the Argonne National Laboratory APS to characterize the source of the unusual magnetism within Sr3CuIrO6.

Scientists are drawn to the unusual properties exhibited by TMCs (copper oxide, for instance, is a key ingredient in many high-temperature superconductors). These compounds typically contain oxygen and a transition metal. Transition metals reside in the middle portion of the Periodic Table of the Elements in groups 3 through 12. The interest in TMCs has largely focused on compounds containing transition metals with lower atomic numbers, specifically the elements scandium through zinc. These elements all lie in the third period of the table, and are collectively referred to as 3d transition metals (indicating their highest electron energy level).

Read more at: Phys.org