Magnetic Hyperfine Interactions of ~(119)Sn Probe Atoms in the Binary Perovskite CaCu_3Mn_4O_(12)

摘要

The manganite CaCu_3Mn_4O_(12) doped by ~(119)Sn atoms (about 1 at % with respect to Mn atoms) is studied by M_ssbauer spectroscopy. The introduction of diamagnetic tin atoms is found not to affect the structure of the manganite. Tetravalent tin atoms are shown to substitute for the isovalent manganese atoms that are located in an octahedral oxygen surrounding. The cluster method of molecular orbitals is used to calculate the contributions of Mn~(4+) and Cu~(2+) cations that belong to different structural sublattices to the hyperfine magnetic field at ~(119)Sn nuclei (H_(Sn) = 105 kOe at T = 77 K). These partial contributions are analyzed, and the intrasublattice Mn~(4+)-O-Mn~(4+) exchange interactions are found to play a significant role in the formation of the magnetic structure of the manganite.