Magnetotransport properties of La0.7 Sr0.3 Mn O3 SrTi O3 superlattices
Journal
Physical Review B - Condensed Matter and Materials Physics
Journal Volume
74
Journal Issue
18
Date Issued
2006
Author(s)
Abstract
The crystalline structures, magnetisms, and magnetotransport properties of La0.7 Sr0.3 Mn O3 SrTi O3 (LSMO/STO) superlattices and La0.7 Sr0.3 Mn O3 (LSMO) films are studied. The transmission electron microscopy images confirm the sharp interfaces and uniformly continuous layers in superlattices and provide the evidence that the superlattices almost have the same in-plane stress while they have a slight increase of out-of-plane strain in LSMO layers for superlattices with thicker STO layers. For the LSMO/STO superlattices with thicker STO or thinner LSMO layers, the decreases in Curie temperature, magnetization, and effective carrier concentration, accompanied by an enhanced residual resistivity, have been observed. In the magnetotransport study, the temperature dependence of longitudinal resistivity ρxx (T), the magnetoresistance ratio (MR) as a function of magnetization M, and the scaling of anomalous Hall coefficient Rs versus longitudinal resistivity ρxx are found to follow the behaviors of ρxx (T) ∼ Tα with α=2.3-2.5, MR=-C [M Ms] 2 with C=1.45-2.17, and - Rs (ρxx) n with n=1.55-2.04, respectively, where Ms is the saturation magnetization. Furthermore, the increased α, and the decreased C and n for superlattices with thicker STO or thinner LSMO layers, are presented. This study provides insight into the effects of decoupling and magnetic disordering on the physical mechanism of the magnetotransport properties of the LSMO/STO superlattices. Our results demonstrate that the interlayer decoupling increases the influence of disorder effects on the magnetism and dominates the magnetotransport phenomenon in LSMO/STO superlattices, while the strain effect plays a minor role on the magnetotransport properties of the overall samples discussed here. © 2006 The American Physical Society.
Type
journal article