Dzyaloshinsky-Moriya Interaction Estimated by AFMR of Kagome Like Substance Cu2O(SO4) Observed at 1.8K

Dolerophanite Cu2O(SO4) is one of model substances for S = 1/2 kagome like antiferromagnet. Although many X-ray diffraction studies have been performed on natural mineral Cu2O(SO4), little is known about its magnetic property. Therefore, the multi-frequency electron spin resonance (ESR) measurements of dolerophanite powder sample have been performed using pulsed magnetic fields up to 16 T in the frequency range from 50 GHz to 315 GHz in the temperature range from 1.8 K to 86 K Antiferromagnetic resonance (AFMR) has been observed below TN = 20 K, which is consistent with the previous magnetic susceptibility result by Asano et al. Moreover, the frequency-field relation at 1.8 K suggests typical easy-plane type AFMR with Dzyaloshinsky-Moriya (DM) interaction, which is also consistent with the weak ferromagnetism below TN suggested by Asano et al. As the estimation of DM interaction is very important to discuss the quantum phase transition in kagome antiferromagnet as suggested by Cépas et al. [2008, Phys. Rev. B 78 140405(R)], we have estimated the D term of DM interaction as 6.98 ± 0.01 K from our AFMR results.