High field ESR measurements on the chiral spin system CuB2O4

Magnetically ordered states in the chiral spin system CuB2O4have been studied by ESR measurements. Two resonance absorptions are observed in the helimagnetic state, which imply that the two inequivalent copper sites are in the helimagnetically ordered state and the paramagnetic state with a development of short range order. The frequency-independent dip with hysteresis on the spectrum is also observed in the helimagnetic state. The behavior of the dip can be interpreted by the change of the dielectric properties rather than the magnetic resonance.