Electronic, magnetic and structural properties of the RFe03 antiferromagnetic-perovskites at very high pressures

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At ambient pressure the orthorhombic perovskites R-orthoferrites (R {triple_bond}Lu, Eu, Y, Pr, and La) exhibit very large optical gaps. These large-gap Mott insulators in which the 3d{sup 5} high-spin ferric ions carry large local moments and magnetically order at T{sub N} > 600 K, undergo a sluggish structural first-order phase transition in the 30-50 GPa range, with the exception of the LuFeO{sub 3} which undergoes an isostructural volume reduction resulting from a high to low-spin crossover. High-pressure methods to 170 GPa using Moessbauer spectroscopy, resistance, and synchrotron-based XRD in diamond anvil cells were applied. Following the quasi-isostructural volume reduction (3-5%) ... continued below

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11 p.

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Pasternak, M.; Xu, W. M.; Rozenberg, G. Kh. (Gregory Kh.) & Taylor, R. D. (R. Dean) January 1, 2002.

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At ambient pressure the orthorhombic perovskites R-orthoferrites (R {triple_bond}Lu, Eu, Y, Pr, and La) exhibit very large optical gaps. These large-gap Mott insulators in which the 3d{sup 5} high-spin ferric ions carry large local moments and magnetically order at T{sub N} > 600 K, undergo a sluggish structural first-order phase transition in the 30-50 GPa range, with the exception of the LuFeO{sub 3} which undergoes an isostructural volume reduction resulting from a high to low-spin crossover. High-pressure methods to 170 GPa using Moessbauer spectroscopy, resistance, and synchrotron-based XRD in diamond anvil cells were applied. Following the quasi-isostructural volume reduction (3-5%) the new phase the magnetic-ordering temperature is drastically reduced, to {approx}100 K, the direct and super-exchange interactions are drastically weakened, and the charge-transfer gap is substantially reduced. The high-pressure (HP) phases of the La and Pr oxides, at their inception, are composed of high- and low-spin Fe{sup 3+} magnetic sublattices, the abundance of the latter increasing with pressure but HP phases of the Eu, Y, and Lu oxides consist solely of low-spin Fe{sup 3+}. Resistance and Moessbauer studies in La and Pr orthoferrites reveal the onset of a metallic state with moments starting at P > 120 GPa. Based on the magnetic and electrical data of the latter species, a Mott phase diagram was established.

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11 p.

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  • Submitted to: Perovskite Materials Symposium, San Francisco, CA, 2002; Proceedings of the Spring 2002 Materials Research Society, Vol. D

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  • Report No.: LA-UR-02-2720
  • Grant Number: none
  • Office of Scientific & Technical Information Report Number: 976174
  • Archival Resource Key: ark:/67531/metadc934773

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  • January 1, 2002

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  • Nov. 13, 2016, 7:26 p.m.

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  • Dec. 12, 2016, 5:48 p.m.

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Pasternak, M.; Xu, W. M.; Rozenberg, G. Kh. (Gregory Kh.) & Taylor, R. D. (R. Dean). Electronic, magnetic and structural properties of the RFe03 antiferromagnetic-perovskites at very high pressures, article, January 1, 2002; United States. (digital.library.unt.edu/ark:/67531/metadc934773/: accessed September 20, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.