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Magnetic State of Ba‐Doped Manganites Depending on the Oxygen Vacancy Concentration
Author(s) -
Trukhanov S.V.,
Kasper N.V.,
Troyanchuk I.O.,
Szymczak H.,
Bärner K.
Publication year - 2002
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200209)233:2<321::aid-pssb321>3.0.co;2-5
Subject(s) - superexchange , magnetization , condensed matter physics , electrical resistivity and conductivity , ferromagnetism , magnetoresistance , materials science , spontaneous magnetization , magnetic moment , vacancy defect , physics , magnetic field , quantum mechanics
Magnetization and electrical transport properties of La 0.60 Ba 0.40 MnO 3— γ (0 ≤ γ ≤ 0.20) anion‐deficient manganites have been studied. Magnetic ordering temperature decreases insignificantly with γ in contrast to spontaneous magnetization. Ferromagnetic metallic ground state of stoichiometric samples ( γ = 0) is destroyed gradually with increasing oxygen vacancy concentration (to γ = 0.20). It is shown that the long‐range ferromagnetic order remains for γ ≤ 0.10 while the cluster spin glass properties appear for 0.10 < γ ≤ 0.20 with temperature of cluster moment freezing of 40 K. Electrical resistivity behavior of the samples with 0 ≤ γ ≤ 0.10 correlates with magnetization. Below the magnetic ordering temperature the resistivity becomes of metallic type and a peak of magnitoresistance is observed. The strongly reduced samples (0.10 < γ ≤ 0.20) have the activated type resistivity and exhibit a large magnetoresistance below the temperature at which the spontaneous magnetization occurs. For the explanation of the obtained results it is assumed that both the Mn 3+ –O–Mn 3+ and the Mn 3+ –O–Mn 4+ magnetic interactions become negative near the oxygen vacancies. The magnetic state of the anion‐deficient samples is interpreted basing on the superexchange interaction model.