High Energy Spin Excitation in Cu3Zn(OD)6FBr

Z2 quantum spin liquid is relatively easier to be identified since one may be satisfied as far as no symmetry breaking and gapped spin excitation continuum are observed. The kagome Heisenberg antiferromagnet ZnCu3(OH)6Cl2 is the most promising candidate for the studying of QSLs with large magnetic interactions and clear sign of continuum excitation. But very limited excitation data has been collected at high energy. We have successfully synthesized Cu3Zn(OH)6FBr with AA kagome stacking. It has no magnetic order down to 50 mK, and a spinon gap with quantum number S=1/2. We have measured spin continuum excitation with a gapped feature. We also measured spin wave in Cu4(OH)6FBr at MARI. The result shows very interesting high energy excitation. We propose to measure Cu3Zn(OH)6FBr up to spin correlation energy level to find the origin of spin continuum excitation.