High frequency ESR studies of two dimensional kagome Lattice antiferromagnet, jarosite KFe3(SO4)2(OH)6

The high frequency ESR studies of the Heisenberg kagomé lattice antiferromagnet, Potassium jarosite KFe3(SO4)2(OH)6 single crystal has been performed by using a MVNA (Millimeter Vector Network Analyzer) system. At the temperature 300K, above the ESR frequency of 100GHz, the ESR spectra have two separated absorptions. The frequency dependence of these absorptions shows liner relations with the g-value of 2.0. These two separated ESR absorption spectra were considered to be caused by the single ion type anisotropy D of Fe3+ magnetic ion. From these analyses of ESR spectra, the single ion type anisotropy D of potassium jarosite, D=25.0GHz (~1.20K) was determined directly for the first time