Magnetic ordering in perovskites A{sub 1{minus}x}MnO{sub 3+y} (A=La, Bi, rare earth ion) (abstract)

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.364720· OSTI ID:496631

Troyanchuk, I O; Kasper, N V ^[1]; Szymczak, H; Nabialek, A ^[2]

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1. Institute of Physics of Solids and Semiconductors, Academy of Sciences of Belarus, 17, P. Brovki, 220072 Minsk (Belarus)
2. Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

In order to clarify the mechanism of exchange interactions in orthomanganites with perovskite structure a magnetic study of parent compounds as a function of stoichiometry has been made. It was shown that the LaMnO{sub 2.99} is a weak ferromagnet with T{sub N}=147 K while LaMnO{sub 3.13} and La{sub 0.9}MnO{sub 3.05} are ferromagnets with T{sub C}=160 and 240 K, respectively. The magnetic data indicate that the mixed magnetic state involving ferro- and antiferromagnetic domains is realized in the intermediate range of oxygen content. The RMnO{sub 3+y} (R=Nd, Sm, Eu, Gd) are inhomogeneous antiferromagnets. The temperatures of start of magnetic moments freezing inside ferromagnetic clusters depend slightly on stoichiometry and for y{approximately}0 are equal 83, 65, 47, and 22 K, respectively. The coercive field for LaMnO{sub 3} is 6 kOe at 4.2 K while that for EuMnO{sub 3} is much higher{emdash}26 kOe. It is worth noting that the Neel temperatures of RMnO{sub 3} (R=Eu, Gd, Tb, Dy) are estimated to be about 40 K independently of the type of rare-earth ion. Magnetic moments of Gd, Tb, and Dy in the rare-earth sublattice are antiferromagnetically ordered below 6{endash}7 K. Applying external fields induces the antiferromagnet{endash}ferromagnet transition in rare-earth sublattice. H{sub cr} at 2 K for RMnO{sub 3} (R=Gd, Tb, Dy) are measured to be about 5, 12, and 10 kOe, respectively. In contrast to rare-earth compounds, the BiMnO{sub 3} is ferromagnet below 98 K. The deviation from stoichiometry as well as replacement of Bi ions by Sr, Ca, or La ions leads to the suppression of the long-range ferromagnetic order. Magnetic properties are discussed in terms of super exchange interactions between manganese ions via oxygen taking into account the 3d-orbital ordering that occurs in LaMnO{sub 3} and TbMnO{sub 3} at 400 and 1200{degree}C, respectively. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 496631
• Report Number(s): CONF-961141--
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
BISMUTH COMPOUNDS
BISMUTH OXIDES
CALCIUM IONS
COERCIVE FORCE
EUROPIUM IONS
GADOLINIUM IONS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MANGANESE OXIDES
NEEL TEMPERATURE
RARE EARTH COMPOUNDS
SAMARIUM IONS
STOICHIOMETRY
STRONTIUM IONS