Sign 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

Conference · Sat Mar 01 00:00:00 EST 1997

OSTI ID:521660

Argyriou, D N; Mitchell, J F; Chmaissem, O; Short, S; Jorgensen, J D ^[1]; Goodenough, J B ^[2]

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1. Argonne National Lab., IL (United States)
2. Univ. of Texas, Austin, TX (United States). Center for Material Science and Engineering

The 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.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States); Welch (Robert A.) Foundation, Houston, TX (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 521660
• Report Number(s): ANL/MSD/CP--91963; CONF-9703106--1; ON: DE97007006; CNN: Grant NSF DMR 91-20000
• Resource Type: Conference paper/presentation
• Conference Information: American Physical Society meeting, Kansas City, MO (United States), 17-21 Mar 1997
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL BONDS
CRYSTAL STRUCTURE
CURIE POINT
LANTHANUM OXIDES
MANGANESE OXIDES
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
STRONTIUM OXIDES
TEMPERATURE DEPENDENCE