Chemical pressure control of Curie temperature in La0.6(Ba0.4−xCax)MnO3

The effects on structural and paramagnetic to ferromagnetic transitions by isovalent chemical substitution of smaller Ca2+ into the bigger Ba2+ sites in La0.6(Ba0.4−xCax)MnO3 (0≤x≤0.4) are investigated. With increasing x, a change from the rhombohedral cell (space group: R-3c) to an orthorhombic cell (space group: Pbnm) is observed. For x≥0.3, the structural transformation leads to an increase in the Mn–O(1) bond length along the c-axis which corresponds to the Jahn–Teller distortion of the distorted MnO6 octahedra in the orthorhombic cell. This effect gives rise to a decrease in TC (the temperature of the paramagnetic to ferromagnetic transition) with increasing Ca content.