Phase diagram and quantum criticality in Shastry-Sutherland lattice BaNd₂ZnS₅

The Shastry-Sutherland (SS) model originally focuses on the antiferromagnetic interactions between nearest-neighbors and alternating next-nearest-neighbors in a two-dimensional square lattice. The original SS model predicted the emergence of various magnetic phases, including spin liquid phases, magnetic superlattice structures, and canted spin phases that bear magnetic analogies to the supersolid phase. BaNd₂ZnS₅ has a topologically equivalent lattice structure with the SS model. The magnetically ordered state is destabilized by external magnetic field and the emergence of a liquid-like state has been proposed. Here, we studied the magnetic field-induced ground state of BaNd₂ZnS₅ using magnetization, resonant ultrasound spectroscopy, ac magnetic susceptibility, and specific heat measurement at low temperature; a series of phase transitions were identified for H along (110). Near 2 T, when q₂ = (-1/2, 1/2, 0) is completely suppressed showing signatures of quantum criticality in various measurements while q₁ = (1/2, 1/2, 0) remains intact up to 12 T.