Single valence and structural order in the colossal-magnetoresistant pyrochlore Tl{sub 2}Mn{sub 2}O{sub 7}
- Chemistry and Materials Sciences Department, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
- Physics Department, University of California, Santa Cruz, California 95064 (United States)
- Dupont Central Research and Development, Experimental Station, Wilmington, Delaware 19880 (United States)
Without Mn{sup 3+}/Mn{sup 4+} mixed-valence or Jahn-Teller distortions in the MnO{sub 6} octahedra, the origin of colossal magnetoresistance (CMR) in the pyrochlore Tl{sub 2}Mn{sub 2}O{sub 7} is thought to arise instead from superexchange with large incoherent scattering near the ferromagnetic transition. Using x-ray-absorption spectroscopy, we have shown that the electronic state of Tl is nearly identical to that in Tl{sub 2}O{sub 3}, indicating doping into the Tl6s bands, that there is no appreciable Mn mixed valence, and that the MnO{sub 6} octahedra are well ordered. This further supports the proposed mechanism for CMR in Tl{sub 2}Mn{sub 2}O{sub 7} based on our earlier structural studies. {copyright} {ital 1997} {ital The American Physical Society}
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 439048
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 2; Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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