Evolution of spin-wave excitations in ferromagnetic metallic manganites.
Neutron scattering results are presented for spin-wave excitations of three ferromagnetic metallic A1-xA'xMnO3 manganites (where A and A' are rare- and alkaline-earth-metal ions), which when combined with previous work elucidate the systematics of the interactions as a function of carrier concentration x, on-site disorder, and strength of the lattice distortion. The long-wavelength spin dynamics show only a very weak dependence across the series. The ratio of fourth to first neighbor exchange (J4/J1) that controls the zone boundary magnon softening changes systematically with x, but does not depend on the other parameters. None of the prevailing models can account for these behaviors.
Center for Neutron Scattering, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA.
F
F
Ye
Pengcheng
P
Dai
J A
JA
Fernandez-Baca
Hao
H
Sha
J W
JW
Lynn
H
H
Kawano-Furukawa
Y
Y
Tomioka
Y
Y
Tokura
Jiandi
J
Zhang