An unprecedented “magnon gap” of Sr3Ir2O7 was revealed using resonant inelastic x-ray scattering beamline at the XSD 9-ID beamline at the APS. This implies that dipolar interactions, analogous to classical bar magnets, are extremely strong in a composite spin-orbit coupled state and that these interactions control the behavior of magnetic moments at the quantum level.


New physics in iridium compounds

December 13, 2012 by Yvonne Carts-Powell

(Phys.org)—Unraveling the complexities of spin-orbital coupling could someday lead to new high-temperature superconductors and workable quantum computers via an elusive phase of matter called a “quantum spin liquid.” Two groups of researchers utilizing x-ray beamlines at the U.S. Department of Energy’s Advanced Photon Source (APS) at Argonne National Laboratory are delving into the new physics required to develop just such a material.

The electrons that surround an atom’s nucleus usually possess independent degrees of freedom including orbital momentum and spin. But in certain circumstances, these two entangle, resulting in a composite state. Spin-orbital coupling is not a new phenomenon, but the way it alters the behavior of novel materials is not yet well-understood.

Because these materials have great fundamental and technological promise, deciphering the effects of spin-orbital coupling is a research priority. Iridates are being explored now because they are one of very few systems that have been predicted to behave as quantum spin liquids, and because tools were developed that can reliably study the spin-orbital coupling. One such tool is resonant inelastic x-ray scattering (RIXS), which is available to users of the APS.

Read more: New physics in iridium compounds — phys.org.

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