Electron-spectroscopy study of the semiconductor-metal transition in $La_{1-x}Sr_xCoO_3$

Chainani, A and Mathew, M and Sarma, DD (1992) Electron-spectroscopy study of the semiconductor-metal transition in $La_{1-x}Sr_xCoO_3$. In: Physical Review B, 46 (16). pp. 9976-9983.

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Abstract

A study of the semiconductor-metal transition in the series $La_{1-x}Sr_xCoO_3$, x=0.0–0.4, using electron-spectroscopy techniques is presented. The results show that the ground state of $LaCoO_3$ has strongly mixed character. From the experiments we estimate the on-site Coulomb correlation energies $U_{dd}$ and $U_{pp}$ to be 3.4 and 6.7 eV, respectively, while the $(pd_\sigma)$ interaction strength is 2.2 eV. A comparison of the experiment with the results of a model many-body cluster calculation for the Co 2p spectra indicates a low-spin state of Co in $LaCoO_3$. The band gap of $LaCoO_3$ is estimated to be about 0.6 eV from ultraviolet photoemission spectroscopy and bremsstrahlung isochromat spectroscopy measurements. The semiconductor-metal transition results from overlap of doped hole states with the valence band for $x\geq0.2$.

Item Type: Journal Article Copyright of this article belongs to American Physical Society. Division of Chemical Sciences > Solid State & Structural Chemistry Unit 13 Oct 2006 19 Sep 2010 04:31 http://eprints.iisc.ernet.in/id/eprint/8251