Moessbauer studies of Sr{sub 2}FeO{sub 4} to pressures of 20 GPa

Conference · Fri Sep 01 04:00:00 EDT 1995

OSTI ID:102400

Hearne, G R ^[1]; Pasternak, M P; Rozenberg, G ^[2]

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1. Univ. of the Witwaterstrand, Johannesburg-Gauteng (South Africa). Dept. of Physics
2. Tel-Aviv Univ. (Israel). School of Physics and Astronomy; and others

The transport and magnetic properties of the antiferromagnetic semiconductor Sr{sub 2}FeO{sub 4} (Fe{sup 4+}, d{sup 4}) were probed by resistance studies and {sup 57}Fe Moessbauer spectroscopy to 20 GPa using a diamond-anvil cell. The main conclusions of this work are that beyond the onset of the semiconductor-metal transition at {approx}17(1) GPa determined in the resistance studies: (1) the compound is still magnetic and, (2) there is no charge disproportionation of the form: 2Fe{sup 4+} {yields} Fe{sup 3+} + Fe{sup 5+}. The quadrupole splitting ({delta}E{sub Q}) at room temperature (RT) decreases from 0.42 mm/s at ambient pressure to a minimum of 2.2 mm/s at {approx}5.5 GPa. Beyond 5.5 GPa {delta}E{sub Q} at RT increases monotonically reaching 0.5 mm/s at 20 GPa. In the 0-10 GPa pressure range the Neel temperature T{sub N}, is pinned at 60-70 K reaching values of 135(5) K at 19 GPa where the compound is metallic. At 19 GPa and T {much_lt} T{sub N} a simplified magnetic spectrum having an internal magnetic field of {approx}25 T and a substantial quadrupole interaction is obtained.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States); United States-Israel Binational Science Foundation, Jerusalem (Israel)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 102400
• Report Number(s): LA-UR--95-2120; CONF-950948--2; ON: DE95016872
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
IRON OXIDES
MAGNETIC PROPERTIES
NEEL TEMPERATURE
PRESSURE DEPENDENCE
SEMICONDUCTOR MATERIALS
STRONTIUM OXIDES
TEMPERATURE DEPENDENCE