Collective magnetic excitation in a single-chain magnet by electron spin resonance measurements

Collective magnetic excitation of the single-chain magnet (SCM) has been observed using high-frequency electron spin resonance (ESR). The observed ESR mode is attributed to the spin wave excitation with strong magnetic anisotropy where its temperature dependence shows the continuous evolution of the short-range spin correlation inside the chain. The uniaxial anisotropy constants and the exchange couplings of the related SCM have been quantitatively deduced from our theoretical analysis. Moreover, the relaxation mechanism of the SCM is found to originate from a collective reversal of spins via the transverse exchange couplings between the molecular units.