Dramatic changes in the magnetic coupling mechanism for La-doped CaMnO3.
The exchange interactions in polycrystalline samples of Ca1-xLaxMnO3 (0.00< or =x< or =0.05) are studied by means of Raman scattering and electron paramagnetic resonance. Dramatic reductions in the spin-phonon interactions and magnetic correlations are observed for La doping levels as small as approximately 2%-3%. These results show that the charge carriers play an important role in the overall exchange coupling in the electron-doped manganites, even at very low doping levels.
Granado
E
E
Instituto de Física "Gleb Wataghin," UNICAMP, 13083-970, Campinas-SP, Brazil.
Moreno
N O
NO
Martinho
H
H
García
A
A
Sanjurjo
J A
JA
Torriani
I
I
Rettori
C
C
Neumeier
J J
JJ
Oseroff
S B
SB