Neutron scattering investigation of magnetic bilayer correlations in $La_{1.2}Sr_{1.8}Mn_2O_7$

摘要

Neutron scattering investigations of the paramagnetic correlations in thelayered manganite La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$, which exhibits colossalmagnetoresistance above the Curie transition at T$_C$ = 112 K, show that spinsin neighboring layers within each bilayer are strongly canted at an averageangle that is dependent on both the magnetic field and temperature, aspredicted by de Gennes. The in-plane correlation length does not diverge atT$_C$, although the magnetic Bragg intensity obeys critical scaling belowT$_C$, with the same temperature dependence as the zero-field electricalconductance.