Ion-Exchange Reactions for Two-Dimensional Quantum Antiferromagnetism

Abstract

A simple geometrical consideration reveals that the magnetism of (CuX)An-1BnO3n+1 is described by a square-lattice J1-J2 model, where J1 and J2 represent the nearest neighbor (NN) interaction and the 2nd NN interaction (Figure 1(c)). According to the GoodenoughKanamori rule, J1 and J2 are expected to be ferromagnetic (FM) and antiferromagnetic (AFM), respectively, giving a situation where geometrical frustration is present in the lattice. The J1-J2 model was originally proposed to explain the origin of high-Tc superconductivity in carrier-doped cuprates with S = 1/2 square lattice [13]. Although the detail of theoretical phase diagram is still controversial [14][15][16][17][18], regardless of the approaches employed, several interesting phases appear as a function of  = J2/J1 (see Figure 2). Let us define hereafter positive and negative J as AFM and FM interaction, respectively. The most interesting phase