Magnetism of manganite nanotubes constituted by assembled nanoparticles

CURIALE, SÁNCHEZ, TROIANI, RAMOS, PASTORIZA, LEYVA, AND LEVY

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

APS

Lugar: APS; Año: 2007 vol. 75 p. 224410 - 224410

0163-1829

We present a study on the magnetic properties of manganite ultrafine grains assembled in nanotubes of 800 nm of external diameter and 6–8
m length. The study includes two homogeneous ferromagnetic com-pounds, La 0.67 Ca 0.33 MnO 3 and La 0.67 Sr 0.33 MnO 3 , and one exhibiting ferromagnetic and charge-ordered phase coexistence, La 0.325 Pr 0.300 Ca 0.375 MnO 3 . From magnetic measurements, we conclude that the grains behave assingle magnetic domains. Observations of dipolar interactions between magnetic grains are evidenced by isothermal remanent magnetization and direct current demagnetization experiments. These experiments suggest that the grain magnetic moments should be arranged in a fanning configuration at H=0. Also, a uniaxial shape anisotropy was observed on previously aligned ferromagnetic nanotubes by ferromagnetic-resonance experi-ences. In La 0.325 Pr 0.300 Ca 0.375 MnO 3 , we observe distinctive features related to its inhomogeneous character ascompared with the ferromagnetic homogeneous nanotubes._end_abstract_PRB_2007