Quantum phase transition between spin solid and liquid states on kagome antiferromagnet

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I have tried to control the ground states and the spin dynamics of the kagome antiferromagnets (KAF) by synthesizing the systematic mixture system of two kinds of fluoride kagome compounds which have the different ground states. An end member of the mixture system has the antiferromagneticallyordered state. Another end member has the non-magnetic pinwheel VBS state as the ground state. It was found that the phase transition temperature and the excitation energies from non-magnetic ground state to first excited magnetic state exhibit systematical change from the results of magnetic measurements carried out for the samples with various mixing ratio. In the first year of this project, first trial of the inelastic neutron scattering experiments using the single crystal have been performed, however, any strong magnetic excitations were not observed because of the broadening of the excitation signals caused by the randomness effects. At the end of the period of the present project, sufficiently large crystals suitable for the neutron scattering experiments were obtained. A detailed research for magnetic excitations for the mixed system will be performed using the neutron time-of-flight spectrometers, which has the advantage of counting efficiency for the low dimensional antiferromagnetic system.