Magnetic resonance in the spin-Peierls compoundα′−NaV2O5

We present results from magnetic-resonance measurements for 75--350 GHz in ${\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{-}{\mathrm{NaV}}_{2}{\mathrm{O}}_{5}.$ The temperature dependence of the integrated intensity indicates that we observe transitions in the excited state. A quantitative description gives resonances in the triplet state at high-symmetry points of the excitation spectrum of this spin-Peierls compound. This energy has the same temperature dependence as the spin-Peierls gap. Similarities and differences with another inorganic compound ${\mathrm{CuGeO}}_{3}$ are discussed.