Electron spin resonance in the spin-Peierls compoundNaV2O5

Single crystals of the spin-Peierls compound NaV${}_2$O${}_5$ were synthesized. Both magnetic susceptibility and the electron-spin-resonance (ESR) intensity measured at 36.2 GHz showed an abrupt decrease at 35 K, indicating transition into the dimerized state. This decrease was much more pronounced for the ESR intensity as compared with the static susceptibility. The temperature dependences of the static and dynamic susceptibilities correspond to an energy gap of 92 K in the magnetic excitation spectrum. At low temperatures significant broadening of the ESR line was observed and a complex signal consisting of three spectral components was found.