Raman investigation of the layered manganese perovskite La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7}

Book · Thu Dec 31 04:00:00 EST 1998

OSTI ID:323424

Romero, D B ^[1]; Podobedov, V B ^[1]; Weber, A; Rice, J P ^[1]; Mitchell, J F ^[2]; Sharma, R P; Drew, H D ^[3]

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1. National Inst. of Standards and Technology, Gaithersburg, MD (United States). Optical Technology Div.
2. Argonne National Lab., IL (United States). Materials Science Div.
3. Univ. of Maryland, College Park, MD (United States). Dept. of Physics

The authors report the results of a detailed polarization and temperature dependence study of the Raman scattering from La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7}. The Raman spectra reveal three general spectral features. First, there are sharp peaks due to long-wavelength optic phonons. Phonons, attributed to the distortion of the MnO{sub 6} octahedra, reveal an anomalous behavior which correlates with the transition from a paramagnetic-insulating (PI) to a ferromagnetic-metallic (FM) phase at a critical temperature {Tc}. Second, there is an electronic continuum that is suppressed for {omega} < 500 cm{sup {minus}1} at T {much_lt} {Tc}. Third, broad peaks between 400 cm{sup {minus}1} to 800 cm{sup {minus}1} seen in the PI state, surprisingly, disappear in the FM state. The implications of these results are discussed.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 323424
• Report Number(s): CONF-971201--; ISBN 1-55899-399-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
EXPERIMENTAL DATA
LANTHANUM OXIDES
MANGANESE OXIDES
MONOCRYSTALS
PHONONS
RAMAN SPECTROSCOPY
STRONTIUM OXIDES
TEMPERATURE DEPENDENCE