Spin-liquid behavior of the three-dimensional magnetic system Ba3NiIr2 O9 with S=1

Abstract

"The quantum spin liquid (QSL) is an exotic phase of magnetic materials where the spins continue to fluctuate without any symmetry breaking down to zero temperature. Among the handful reports of QSL with spin S 1, examples with magnetic ions on a three-dimensional (3D) magnetic lattice are extremely rare since both larger spin and higher dimension tend to suppress quantum fluctuations. In this work, we offer a new strategy to achieve 3D QSL with high spin by utilizing two types of transition metal ions; both are magnetically active but located at crystallographically inequivalent positions. We design a 3D magnetic system Ba3NiIr2O9 consisting of interconnected corner-shared NiO6 octahedra and face-shared Ir2O9 dimer, both having triangular arrangementsin a-b plane. X-ray absorption spectroscopy measurements confirm the presence of Ni2+ (S = 1). Our detailedthermodynamic and magnetic measurements reveal that this compound is a realization of gapless QSL state down to at least 100 mK. Ab initio calculations find a strong magnetic exchange between Ir and Ni sublattices andin-plane antiferromagnetic coupling between the dimers, resulting in dynamically fluctuating magnetic moments."