a Departmento de Física Aplicada, Universidade de Santiago de Compostela, E-15782, Santiago de Compostela, Spain
b Departmento de Química-Física, Universidade de Santiago de Compostela, E-15782, Santiago de Compostela, Spain
Abstract:
A criterion used for the determination of first- and second-order magnetic phase transitions from purely magnetic methods is applied to manganese perovskites of formula La2/3(Ca1−xSrx)1/3MnO3. A crossover from first- to second-order character at a tolerance factor t=0.92 is found, which also brings about several variations in other physical properties. At t=0.92 a change from orthorhombic to rhombohedral symmetry also takes place. The impossibility of establishing static cooperative Jahn–Teller distortions in the rhombohedral symmetry is suggested as being responsible for the observed behaviour.