Structural, magnetic, and electrical properties of single-crystalline (formula presented) (formula presented)

Abstract

We report on structural, magnetic, and electrical properties of Sr-doped (formula presented) single crystals for doping levels (formula presented) The complex structural and magnetic phase diagram can only be explained assuming significant contributions from the orbital degrees of freedom. Close to (formula presented) a ferromagnetic metal is followed by an antiferromagnetic metallic phase below 200 K. This antiferromagnetic metallic phase exists in a monoclinic crystallographic structure. Following theoretical predictions this metallic antiferromagnet is expected to reveal an (formula presented) -type orbital order. For higher Sr concentrations an antiferromagnetic insulator is established below room temperature. © 2002 The American Physical Society.