Exact Dimer Ground State and Quantized Magnetization Plateaus in the Two-Dimensional Spin SystemSrCu2(BO3)2

Abstract

Magnetic susceptibility, Cu NQR, and high-filed magnetization have been measured in polycrystalline $\mathrm{SrCu}{}_2(\mathrm{BO}{}_3{)}_2$ having a two-dimensional (2D) orthogonal network of Cu dimers. This cuprate provides a new class of 2D spin-gap system $(\Delta =30\mathrm{}\mathrm{K})$ in which the ground state can be solved “exactly.” Furthermore, in the magnetization, two plateaus corresponding to $\frac{1}{4}$ and $\frac{1}{8}$ of the full Cu moment were first observed for 2D quantum spin systems.