Excitation Spectrum and Superexchange Pathways in the Spin Dimer VODPO 4 ̇ 1 2 D 2 </…
1997; American Physical Society; Volume: 78; Issue: 26 Linguagem: Inglês
10.1103/physrevlett.78.4998
ISSN1092-0145
AutoresD. M. Tennant, S. E. Nagler, A. W. Garrett, T. Barnes, C.C. Torardi,
Tópico(s)Magnetism in coordination complexes
ResumoMagnetic excitations have been investigated in the spin dimer material VODPO_4 \cdot 1/2 D_2O using inelastic neutron scattering. A dispersionless magnetic mode was observed at an energy of 7.81(4) meV. The wavevector dependence of the scattering intensityfrom this mode is consistent with the excitation of isolated V^{4+} spin dimers with a V-V separation of 4.43(7) \AA. This result is unexpected since the V-V pair previously thought to constitute themagnetic dimer has a separation of 3.09 \AA. We identify an alternative V-V pair as the likely magnetic dimer, which involves superexchange pathways through a covalently bonded PO_4 group. This surprising result casts doubt on the interpretation of (VO)_2P_2O_7 as a spin ladder.
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