Orbital order in layered manganites probed with 57Fe Mössbauer spectroscopy

摘要

In mixed-valence manganites, the doped iron species play the roles of simultaneous probes and ruiners for the orbital order occurring in the Mn-O electronic subsystem. We investigated the Mn3 + -based undoped system RBaMn2O5.5 and the half-doped systems RBaMn2O6, and RBaMn2O5 substituting a tiny portion of Mn3 + sites with Fe3 + . Single-site Mössbauer spectra were observed at room temperature in the charge-orbitally ordered state, i.e., below TCOO, for R=Y, Sm, Gd. Size of the rare earth ion strongly influences the quadrupole splitting in RBaMn2O6, but not in RBaMn2O5.