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<p>The structural, morphological, and electronic transport properties of La<sub>0.5</sub>Ca<sub>x</sub>Sr<sub>0.4-x</sub>Ag<sub>0.1</sub>MnO<sub>3</sub> (x = 0.1–0.4) composites were investigated in this study. X-ray diffraction confirmed an orthorhombic Pnma perovskite structure with a metallic Ag secondary phase, indicating Ag segregation at the grain boundaries rather than substitution for La<sup>3</sup>⁺. The electrical resistivity exhibited insulator-to-metal transitions, with transition temperatures dependent on Ca<sup>2</sup>⁺ concentration. High-temperature transport is better described by the variable-range hopping (VRH) model than by the small-polaron hopping (SPH) model, indicating carrier hopping between localized states. Low-temperature transport was analyzed using electron–electron scattering and weak localization. The magnetoresistance (MR) was measured from 2 to 300&#xa0;K up to 10&#xa0;T. A maximum extrinsic MR of 68.38% was observed at 2&#xa0;K and 10&#xa0;T for x = 0.3, which was attributed to spin-polarized tunneling at the grain boundaries. At 300&#xa0;K, the MR reaches 18.53% at 10&#xa0;T for x = 0.3, whereas at 1&#xa0;T, it is ≤ 0.31% for all compositions. The large low-temperature MR provides insights into spin-dependent grain-boundary transport. Enhancing room-temperature, low-field MR remains a key challenge for device applications.</p>

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Magneto-transport characteristics of La0.5CaxSr0.4-xAg0.1MnO3(x = 0.1–0.4) manganite nanoarchitectonics

  • 期刊论文

  • 发表日期：

    2026年7月31日

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  • P. Subhashini,
  • B. Munirathinum,
  • Pragna Puppala,
  • Sankararao Yadam,
  • S. Shanmukharao Samatham,
  • R. Venkatesh,
  • V. Ganesan

摘要

The structural, morphological, and electronic transport properties of La0.5CaxSr0.4-xAg0.1MnO3 (x = 0.1–0.4) composites were investigated in this study. X-ray diffraction confirmed an orthorhombic Pnma perovskite structure with a metallic Ag secondary phase, indicating Ag segregation at the grain boundaries rather than substitution for La3⁺. The electrical resistivity exhibited insulator-to-metal transitions, with transition temperatures dependent on Ca2⁺ concentration. High-temperature transport is better described by the variable-range hopping (VRH) model than by the small-polaron hopping (SPH) model, indicating carrier hopping between localized states. Low-temperature transport was analyzed using electron–electron scattering and weak localization. The magnetoresistance (MR) was measured from 2 to 300 K up to 10 T. A maximum extrinsic MR of 68.38% was observed at 2 K and 10 T for x = 0.3, which was attributed to spin-polarized tunneling at the grain boundaries. At 300 K, the MR reaches 18.53% at 10 T for x = 0.3, whereas at 1 T, it is ≤ 0.31% for all compositions. The large low-temperature MR provides insights into spin-dependent grain-boundary transport. Enhancing room-temperature, low-field MR remains a key challenge for device applications.