## Abstract

(Formula presented) with a perovskite-related structure, represented as (Formula presented) undergoes a semiconductor-to-metal transition (Formula presented) at 210 K, orders ferromagnetically (Formula presented) at 340 K, and exhibits giant magnetoresistance (GMR). In contrast to the rare-earth manganate-based (Formula presented) perovskites, which exhibit colossal magnetoresistance (CMR) near (Formula presented) for (Formula presented) the MR increases smoothly with decreasing temperature and the largest MR is not near the SM transition. X-ray-absorption spectra indicate that the formal oxidation states are consistent with (Formula presented) Thus the double-exchange (Formula presented) magnetic interactions invoked as the mechanism of CMR in perovskite manganates cannot be important in this compound. The dramatic differences observed in the properties of (Formula presented) from those of the mixed-valent rare-earth manganates suggest a fundamentally different mechanism for the origin of the large MR. The magnetic coupling between (Formula presented) ions on the (Formula presented) site, (Formula presented) ions on the (Formula presented) site and possible interactions between the (Formula presented)- and (Formula presented)-site magnetic ions are responsible for the observed differences in behavior of (Formula presented) from those of the CMR manganates with only one type of magnetic ion. (Formula presented) exhibits high sensitivity to (Formula presented) at low fields, and good thermal stability of the MR. These properties are advantageous for magnetic storage applications.

Original language | English (US) |
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Pages (from-to) | R595-R598 |

Journal | Physical Review B - Condensed Matter and Materials Physics |

Volume | 58 |

Issue number | 2 |

DOIs | |

State | Published - Jan 1 1998 |

## All Science Journal Classification (ASJC) codes

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics