| Autor: |
Woodward, Patrick M., Goldberger, Joshua, Stoltzfus, Matthew W., Eng, Hank W., Ricciardo, Rebecca A., Santhosh, Padmam N., Karen, Pavel, Moodenbaugh, Arnold R. |
| Předmět: |
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| Zdroj: |
Journal of the American Ceramic Society; Jun2008, Vol. 91 Issue 6, p1796-1806, 11p, 2 Black and White Photographs, 2 Diagrams, 5 Charts, 7 Graphs |
| Abstrakt: |
The perovskites Sr2MnRuO6 and LaSrMnRuO6 have been investigated and their properties compared with those of the broader family of A2MRuO6 double perovskites (A=Sr, La; M=Cr, Mn, Fe, Co, Ni). Neutron powder diffraction shows that both phases lack long-range Mn/Ru order. Sr2MnRuO6 exhibits a cooperative Jahn–Teller distortion, conductivity that proceeds via variable-range hopping, and antiferromagnetic (AFM) order (C-type structure, TN≅200K, 2.05(1) μB per transition metal). LaSrMnRuO6 exhibits nearly undistorted octahedra, conductivity that proceeds via diffusion-assisted small-polaron hopping, and ferromagnetic (FM) order ( TC≅220K, 1.60(4) μB transition metal). Band structure calculations show that AFM Mn–O–Ru coupling optimizes polarization of the Ru t2 g orbitals, while FM coupling favors delocalization of the Ru t2 g electrons. The transition from antiferromagnetism to ferromagnetism is linked to a loss of orbital order and stabilized over competing glassy states by delocalization of Ru t2 g electrons. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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