## Abstract

We have studied the magnetic cluster compound Nb_{6}F_{15} which has an odd number of 15 valence electrons per (Nb_{6}F_{12})^{3+} cluster core, as a function of temperature using nuclear magnetic resonance, magnetic susceptibility, electron magnetic resonance and neutron powder diffraction. Nuclear magnetic resonance of the ^{19}F nuclei shows two lines corresponding to the apical F^{a-a} nucleus, and to the inner F^{i} nuclei. The temperature dependence of the signal from the F^{i} nuclei reveals an antiferromagnetic ordering at T < 5 K, with a hyperfine field of ~2 mT. Magnetic susceptibility exhibits a Curie-Weiss behavior with T_{N} ~5 K, and μ_{eff} ~1. 57 μ_{B} close to the expected theoretical value for one unpaired electron (1. 73 μ_{B}). Electron magnetic resonance linewidth shows a transition at 5 K. Upon cooling from 10 to 1. 4 K, the neutron diffraction shows a decrease in the intensity of the low-angle diffuse scattering below Q ~0. 27 Å^{-1}. This decrease is consistent with emergence of magnetic order of large magnetic objects (clusters). This study shows that Nb_{6}F_{15} is paramagnetic at RT and undergoes a transition to antiferromagnetic order at 5 K. This unique antiferromagnetic ordering results from the interaction between magnetic spins delocalized over each entire (Nb_{6}F_{12}^{i})^{3+} cluster core, rather than the common magnetic ordering.

Original language | English |
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Pages (from-to) | 143-151 |

Number of pages | 9 |

Journal | Applied Magnetic Resonance |

Volume | 44 |

Issue number | 1-2 |

DOIs | |

State | Published - 1 Feb 2013 |

## ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

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