Structural, magnetic and electrical properties of double-doped manganites Y0.5+ySr0.5−yMn1−yCryO3 (0≤y≤0.5)

Abstract We report an investigation on the evolution of structural, magnetic and transport properties in double-doped manganites Y 0.5+ y Sr 0.5− y Mn 1− y Cr y O 3 (0≤ y ≤0.5), remaining e g electron density ( x =0.5) unchanged. From a pseudo-cubic perovskite structure for Y 0.5 Sr 0.5 MnO 3 with y =0, powder X-ray diffraction patterns demonstrate that Cr 3+ substitution on the Mn-site leads to a tetragonal distortion, which increases with the doping level y . The temperature dependence of magnetic susceptibility shows that the magnetic state at low temperatures evolves from an antiferromagnetic-spin-glass state for y =0, undergoing a ferromagnetic-spin-glass state, finally to a ferrimagnetic state for y =0.5. The electrical transport properties of all samples show an insulator behavior dominated by the small polaron hopping mechanism and the activation energy increases significantly along with y . Consequently, the enhancement of ferromagnetic component in the Y 0.5+ y Sr 0.5− y Mn 1− y Cr y O 3 series may be attributed to the anisotropic ferromagnetic superexchange interactions of Mn 3+ ions collaborating with the ordered arrangement of Mn 3+ /Cr 3+ ions, rather than the double exchange interaction via e g -electron hopping process.