ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
To determine the Tc dependence of the colossal magnetoresistance (CMR) exhibited by the ferromagnetic La0.7A0.3MnO3+δ (A=Ba, Ca, Sr) system, we examine the magnetic-field and temperature-dependent resistivity and magnetization of a series of thin films that were grown via pulsed-laser deposition. The films had magnetic ordering temperatures (Tc) ranging from 150 to 350 K. All samples display a large negative MR that is largest near Tc, and samples with a low Tc display significantly larger MR values than do samples with large Tc's. The quantity ρ(Tc)/ρ(4 K), the amount by which the resistivity is reduced by full ferromagnetic order, varies as exp(Ea/Tc) with an activation energy Ea=0.1 eV. These results indicate that the magnitude of the CMR effect in a given specimen is controlled not by ρ(Tc), but by Tc via the ratio ρ(Tc)/ρ(4 K). Phenomenological scaling relationships are also reported that link ρ(H,T) to both H and M(H,T). © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.361715
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