606 K
17 pp.
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TitleSign Reversal of the MN-O Bond Compressibility in La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} Below T{sub C}: Exchange Striction in the Ferromagnetic State
Author(s)Argyriou, D. N.; Mitchell, J. F.; Chmaissem, O.; Short, S.; Jorgensen, J. D.; Goodenough, J. B.
Publication DateMarch 1997
Report NumberANL/MSD/CP--91963
Unique IdentifierACC0328
Other NumbersCONF-9703106--1; Legacy ID: DE97007006; OSTI ID: 521660
Research OrgArgonne National Laboratory [ANL], IL (United States) ; University of Texas, Austin, TX (United States), Center for Material Science and Engineering
Contract NoW-31109-ENG-38
Sponsoring OrgU.S. Department of Energy (DOE) Office of Energy Research (ER), Washington, DC (United States); National Science Foundation (NSF) Office of Science and Technology Centers, Washington, DC (United States) under Grant NSF DMR 91-20000; Welch (Robert A.) Foundation, Houston, TX (United States)
Other InformationAmerican Physical Society meeting, Kansas City, MO (United States), 17-21 Mar 1997
Subject36 Materials Science; Crystal Structure; Lanthanum Oxides; Strontium Oxides; Manganese Oxides; Physical Properties; Pressure Dependence; Curie Point; Chemical Bonds; Temperature Dependence
Related Web PagesJohn B. Goodenough, Cathode Materials, and Rechargeable Lithium-ion Batteries
AbstractThe crystal structure of the layered perovskite La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7} has been studied under hydrostatic pressure up to {approximately} 6 kbar, in the paramagnetic and ferromagnetic states, with neutron powder diffraction. The compressibility of the Mn-O apical bonds in the double layer of MnO{sub 6} octahedra changes sign from the paramagnetic insulator (PI) to the ferromagnetic metal (FM) state; in the Fm state the Mn-O-Mn linkage between MnO{sub 2} planes expands under applied pressure, whereas they contract in the PI state. This counterintuative behavior is interpreted in terms of exchange striction, which reflect the competition between super- and double-exchange. An increase of the Mn-moment with applied pressure in the FM state is consistent with a positive dT{sub C}/dP, as well as a cant angle {theta}{sub 0} between the magnetizations of neighboring MnO{sub 2} sheets that decreases with pressure.
606 K
17 pp.
View Document 

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