Novel quantum spin liquid state in Ba3ZnRu2O9

We have discovered a novel type of quantum spin liquid in Ba3ZnRu2O9, which has a hexagonal lattice of Ru5+ dimers. In the temperature (T) dependence of the magnetic susceptibility (χ) of Ba3ZnRu2O9, any traces of the Curie tail or glassy behavior have not been detected down to 50 mK. We have studied the magnetic behavior of the Nb-doped system Ba3Zn(Ru1-yNby)2O9, where the Nb5+ (4d)0 is non-magnetic ion and disturbs the formation of the Ru5+ dimer. The χ – T curves of the Nb-doped system also shows no trace of the Curie tail at low temperatures, indicating that the local Ru5+-spin induced by the Nb-doping does not act like a free spin. The spin liquid state of Ba3ZnRu2O9 is found to be robust by impurity doping. In order to study the magnetic dynamics at low temperature, we plan ZF-μSR and LF-μSR measurements of three samples Ba3Zn(Ru1-yNby)2O9 (y = 0, 0.06, and 0.12) down to 50 mK.