Zero-point entropies of spin-jam and spin-glass states in a frustrated magnet

Thermodynamics studies of a prototypical quasi-two-dimensional frustrated magnet, Ba2Sn2ZnCr7pGa10-7pO22, where the magnetic Cr3+ ions are arranged in a triangular network of bipyramids show that the magnetic zero-point entropy for p=0.98 is 55(1)% of the entropy expected when the Cr3+ moments are fully disordered. Furthermore, when combined with a previous neutron scattering study and the perimeter scaling entropy of a spin jam, the analysis reveals that with decreasing p, i.e., doping of the nonmagnetic Ga3+ ions, the variation in the magnetic zero-point entropy can be well explained by the combined effects of the zero-point entropy of the spin jam state and that of weakly coupled orphan spins, shedding light on the coexistence of the two types of spin states in quantum magnetism.