Detailed study of the structural and magnetic transitions in Pr1-xSrxMnO3 single crystals (0.48≤x≤0.57)

The X-ray diffraction, magnetic, electric and specific heat measurements have been performed on single crystals Pr1-xSrxMnO3 close to boundary between the Pbnm and 14/mcm perovskite types where subtle changes of composition are found sufficient for considerable variation of magnetic ground states and character of carriers. The sample of x = 0.48 undergoes a transition from the paramagnetic phase of orthorhombic Pbnm symmetry to the ferromagnetic metallic phase of tetragonal 14/mcm symmetry (T-C = 290 K). The sample of a slightly higher x = 0.50 exhibits the 14/mcm symmetry already in the paramagnetic state. The ferromagnetism below T-C = 265 K is followed at lower temperatures by a transition to the orbitally polarized state of the Fmmm symmetry associated with the A-type anti ferromagnetic arrangement (T-N = 155 K). The end composition of x = 0.57 undergoes the antiferromagnetic transition directly from the paramagnetic state at T-N = 217 K and the experiments confirm the metallic character of the A-type ground state. (C) 2002 Elsevier Science B.V. All rights reserved.