Achieving high anisotropic magnetoresistance in La0.68Sm0.02Ca0.3MnO3:Agx composites near room temperature

Polycrystalline manganese oxides exhibit remarkable tunable magnetoresistance (MR) and anisotropic magnetoresistance (AMR), rendering them highly promising for magnetic sensor applications. However, their practical utilization is hindered by two critical challenges: (i) the requirement of high magnetic fields to achieve optimal electromagnetic properties, and (ii) the deviation of the metal-insulator transition temperature (T MI ) from room temperature. In this study, La 0.68 Sm 0.02 Ca 0.3 MnO 3 :Ag x ( x  = 0.1–0.4) composites were synthesized via sol–gel and solid-phase methods. Notably, at x  = 0.2, exceptional MR and AMR values of 88 % and 123 %, respectively, were achieved near room temperature under a low magnetic field of 1 T. This represents the highest AMR performance reported to date for polycrystalline materials under similar conditions, comparable to thin films. The incorporation of Ag was found to mitigate grain boundary scattering while enhancing interfacial spin polarization, thereby significantly improving MR. The extraordinary AMR is attributed to the anisotropic spin–orbit coupling (SOC) effect. Resistivity data were well–fitted using electron-scattering and small-polaron hopping models, further validating the pivotal role of SOC in enhancing AMR under varying magnetic fields. These findings provide a robust foundation for advancing perovskite manganese oxides in manganite–based device applications.