Charge ordering and phase competition in the layered perovskiteLaSr2Mn2O7
| Autor: | J. S. Gardner, Anthony K. Cheetham, Geoffrey F. Strouse, Branton J. Campbell, D. N. Argyriou, D. E. Cox, Heloisa N. Bordallo, A. M. dos Santos, Khalid M. Hanif |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Physical Review B. 61:15269-15276 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.61.15269 |
| Popis: | Charge-lattice fluctuations are observed in the layered perovskite manganite LaSr{sub 2}Mn{sub 2}O{sub 7} by Raman spectroscopy at temperatures as high as 340 K, and with decreasing temperature they become static, forming a charge-ordered (CO) phase below T{sub CO}=210 K. In the static regime, superlattice reflections are observed by neutron and x-ray diffraction with a propagation vector (1/4, -1/4, 0). Crystallographic analysis of the CO state demonstrates that the degree of charge and orbital ordering in this manganite is weaker than that in the three-dimensional perovskite manganites. Below T{sub N}=170 K, type-A antiferromagnetism (AF) develops and competes with the charge ordering, causing it to eventually melt below T{sup *}=100 K. High-resolution diffraction measurements suggest that the CO and AF states do not coincide within the same region of material, but rather coexist as separate phases. The transition to type-A antiferromagnetism at lower temperatures is characterized by the competition between these two phases. (c) 2000 The American Physical Society. |
| Databáze: | OpenAIRE |
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