The evolution of the short-range structural signature of the Ir 4+ dimer state in CuIr2S4 thiospinel has been studied across the metal-insulator phase transitions as the metallic state is induced by temperature, Cr doping, and x-ray fluence. An atomic pair distribution function (PDF) approach reveals that there are no local dimers that survive into the metallic phase when this is invoked by temperature and doping. The PDF shows Ir4+ dimers when they exist, regardless of whether or not they are long-range ordered. At 100 K, exposure to a 98 keV x-ray beam melts the long-range dimer order within a few seconds, though the local dimers remain intact. This shows that the metallic state accessed on warming and doping is qualitatively different from the state obtained under x-ray irradiation.
E. S. Bozin et al., "Detailed Mapping of the Local Ir⁴⁺ Dimers through the Metal-Insulator Transitions of CuIr₂S₄ Thiospinel by X-ray Atomic Pair Distribution Function Measurements," Physical Review Letters, vol. 106, no. 4, American Physical Society (APS), Jan 2011.
The definitive version is available at https://doi.org/10.1103/PhysRevLett.106.045501
Keywords and Phrases
Atomic Pair Distribution Functions; Cr-doping; Metal-insulator Phase Transition; Metallic Phase; Metallic State; Structural Signatures; X Ray Beam; X Ray Irradiation; X-ray Fluence; Chromium; Dimers; Iridium; Metal Insulator Boundaries; Metal Insulator Transition; Semiconductor Insulator Boundaries; Distribution Functions
International Standard Serial Number (ISSN)
Article - Journal
© 2011 American Physical Society (APS), All rights reserved.
01 Jan 2011