Field-induced ferromagnetic order and colossal magnetoresistance in La(1.2)Sr(1.8)Mn2O7: a 139La NMR study.
In order to gain insights into the origin of colossal magnetoresistance (CMR) in manganese oxides, we performed a 139La NMR study in the double-layered compound La(1.2)Sr(1.8)Mn2O7. We find that above the Curie temperature T(C) = 126 K, applying a magnetic field induces a long-range ferromagnetic order that persists up to T = 330 K. The critical field at which the induced magnetic moment is saturated coincides with the field at which the CMR effect reaches a maximum. Our results therefore indicate that the CMR observed above T(C) in this compound is due to the field-induced ferromagnetism that produces a metallic state via the double exchange interaction.
Department of Physical Science, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan.
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Y
Shiotani
J L
JL
Sarrao
Guo-Qing
GQ
Zheng