Resonance-like magnetic excitations in spinel ferrimagnets FeCr 2O4 and NiCr2O4 observed by neutron scattering

Keisuke Tomiyasu, Haruhiro Hiraka, Kenji Ohoyama, Kazuyoshi Yamada

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23 Citations (Scopus)

Abstract

We performed powder neutron scattering experiments on spinel ferrimagnets ACr2O4 with magnetic and Jahn-Teller A2+ ions (A = Fe, Ni, Cu). In both FeCr2O4 and NiCr 2O4, although geometric frustration had been expected to vanish so far, resonance-like magnetic excitation modes were discovered around Q ≃ 1.4 Å-1 and E ≃ 5 and 8 to 9 meV in a low-temperature magnetic order phase, similar to the local spin resonance modes early reported in highly frustrated spinel antiferromagnets ACr 2O4 with nonmagnetic and non-Jahn-Teller A2+ ions (A = Mg, Zn). In a high-temperature magnetic order phase the resonance-like inelastic scattering transformed into quasielastic scattering. In CuCr 2O4 no such diffusive scattering was observed. We interpret the resonance-like magnetic excitations as a dynamical spin-frustration effect, and discuss a necessary condition for the appearance of them.

Original languageEnglish
Article number124703
Journaljournal of the physical society of japan
Volume77
Issue number12
DOIs
Publication statusPublished - 2008 Dec

Keywords

  • Geometric frustration
  • Hexamer
  • Inelastic neutron scattering
  • Neutron diffraction
  • Spin molecule

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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