Chemical control of colossal magnetoresistance in manganites

The evolution of the structural, electrical and magnetic properties with the isovalent chemical substitution of Ca2+ into the Sr2+ sites in the new series of two-dimensional La1.2(Sr1.8−xCax)Mn2O7 samples (0≤x≤0.8) and three-dimensional La0.6(Sr0.4−xCax)MnO3 samples (0≤x≤0.4) has been investigated. The compositional dependence of the structural variation has been found in La0.6(Sr0.4−xCax)MnO3. The Curie temperatures (TC) decreased from 135 to 102 K and 370 to 270 K for x=0–0.4 in La1.2(Sr1.8−xCax)Mn2O7 and La0.6(Sr0.4−xCax)MnO3, respectively. Our results confirm that the dimensionality as well as ionic size plays an important role in controlling the colossal magnetoresistance in manganites.