Abstract
The magneto transport of Ruddlesden–Popper, La2-2xSr1+2xMn2O7 (0.42≤x≤0.52), 2-dimensional bilayered manganites have been investigated in a broad temperature range. The samples have been synthesized using the solid-state reaction method. Rietveld refinement of the X-ray diffraction data indicates the tetragonal structure formation with I4/mmm space group. The resistivity curves of the samples present a general characteristic of metal-insulator (MI) transition at certain temperature (TMI). Besides, for samples with x = 0.48, 0.50, and 0.52, at a certain temperature (TCO) well below TMI the charge ordering is also evident. Furthermore, the samples display a shallow upturn in resistivity below Tmin due to the Kondo like spin scattering effect, weak localization and electron-phonon interaction. The high temperature semiconducting (T>TMI) region, the resistivity curve follows the 3D Mott’s variable hopping transport mechanism. The overall suppression of resistivity accounts for a substantial magnetoresistance by applying a magnetic field and the characteristic change in TMI, TCO, and Tmin are discussed. Temperature-dependent magnetization demonstrates the suppression of ferromagnetism and evident of antiferromagnetic nature with an apparent charge ordering with increasing concentration of Sr2+.
Highlights
Ruddlesden–Popper compounds having general formula (A)n+1BnO3n+1 {AO(ABO3)n} are a kind of perovskite structure consisting of a two-dimensional (2D) layered structure interspersed with cations (A =La, Sr, and B=Mn) and anions (Oxygen) and n represents the number of layers in perovskite-like array, stacked between rock-salt AO layers along the crystallographic c-axis
The temperature (T) dependent electrical resistivity (ρ) curve for the series of La2-2xSr1+2xMn2O7 (0.42≤x≤ 0.52) measured in the absence (0T) and the in the presence of the applied field (H) is shown in Fig 2 (a–e). It can be observed from these figs that the samples demonstrate the generic metal-insulator transition at a certain temperature (TMI), which for x = 0.42, 0.46, 0.48, 0.50, and 0.52 is approximately 172, 182, 192, 203, and 199 K respectively
The common metal insulator transition at certain temperature (TMI), which falls to higher temperature side on applying the field, is profound and understood owing to double exchange (DE) interactions
Summary
Ruddlesden–Popper compounds having general formula (A)n+1BnO3n+1 {AO(ABO3)n} are a kind of perovskite structure consisting of a two-dimensional (2D) layered structure interspersed with cations (A =La, Sr, and B=Mn) and anions (Oxygen) and n represents the number of layers in perovskite-like array, stacked between rock-salt AO layers along the crystallographic c-axis.. Ruddlesden–Popper compounds having general formula (A)n+1BnO3n+1 {AO(ABO3)n} are a kind of perovskite structure consisting of a two-dimensional (2D) layered structure interspersed with cations (A =La, Sr, and B=Mn) and anions (Oxygen) and n represents the number of layers in perovskite-like array, stacked between rock-salt AO layers along the crystallographic c-axis.1 In this array, the perovskite structure corresponds to n = ∞ and the K2NiF4 structure to n = 1. In this study a comprehensive study of low temperature transport and high temperature semiconducting behavior in La2-2xSr1+2xMn2O7 (0.42≤x≤0.52) are investigated.
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