Detailed study of the structural and magnetic transitions in Pr 1− xSr xMnO 3 single crystals (0.48⩽ x⩽0.57)

Abstract

The X-ray diffraction, magnetic, electric and specific heat measurements have been performed on single crystals Pr 1− x Sr x MnO 3 close to boundary between the Pbnm and I4/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 I4/mcm symmetry ( T C=290 K). The sample of a slightly higher x=0.50 exhibits the I4/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 antiferromagnetic 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.