Metal to insulator transition in Sr2Ru1-xIrxO4

X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and X-ray diffraction (XRD) techniques along with calculations of tight-binding linear muffin tin orbitals within the atomic sphere approximation (TB-LMTO-ASA) have been used for studying the metal to insulator transition (MIT) in the series Sr2Ru1-xIrxO4 Rietveld analysis of the XRD data indicated that the samples of x = 0 to 0.4 are of I4/mmm space group and x = 0.6 and 1.0 are of I4(1)/acd space group. A drastic increase of Ru (Ir)-O1 bond length is observed between x = 0.4 and 0.6. UPS data showed finite density of slates (DOS) at E-F for the samples of x = 0.0 to 0.4, whereas no DOS at E-F was observed for x = 0.6 and 1.0 samples, indicating an MIT between x = 0.4 and 0.6, On the contrary, linear muffin tin orbitals (LMTO) calculations show a finite DOS at E-F for Sr2IrO4 (x = 1.0) With a gap of 1.2 eV in the DOS which starts 0.3 above E-F A large spectral weight transfer is seen in UPS conduction bands. These results indicate that the MIT observed in the Sr2Ru1-xIrxO4 series is a combined effect of structure and electron correlation effects. (C) 2000 Elsevier Science Ltd. All rights reserved.