## Abstract

The T dependence (formula presented) of the electron paramagnetic resonance (EPR), magnetic susceptibility (formula presented) and specific heat (formula presented) of the normal antiferromagnetic (AFM) spinel (formula presented) and the spin-glass (SG) (formula presented) (formula presented) are reported. These systems behave as a strongly frustrated AFM and SG with (formula presented) and (formula presented) At high-T the EPR intensity follows the (formula presented) and the g value is T independent. The linewidth broadens as the temperature is lowered, suggesting the existence of short range AFM correlations in the paramagnetic phase. For (formula presented) the EPR intensity and (formula presented) decreases below 90 and (formula presented) respectively. These results are discussed in terms of both nearest-neighbor (formula presented) (formula presented) spin-coupled pairs and spin-coupled tetrahedral clusters with an exchange coupling of (formula presented) The appearance of small resonance modes for (formula presented) the observation of a sharp drop in (formula presented) and a strong peak in (formula presented) at (formula presented) confirms, as previously reported, the existence of long range AFM correlations in the low-T phase. A comparison with recent neutron diffraction experiments, that found a near dispersionless excitation at 4.5 meV for (formula presented) and a continuous gapless spectrum for (formula presented) is also given.

Original language | English (US) |
---|---|

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

Volume | 64 |

Issue number | 2 |

DOIs | |

State | Published - 2001 |

## All Science Journal Classification (ASJC) codes

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics