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 T-N = 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 T-N 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 Cepas et al : [2008, Phys. Rev. B 7 8 140405(R)], we have estimated the D term of DM interaction as 6.98 +/- 0.01 K from our AFMR results.