Magnetization process of the = 1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice

Nakano, Hiroki*; Isoda, Makoto*; Sakai, Toru

We study the = 1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice by the numerical diagonalization. We tune the ratio of two antiferromagnetic interactions coming from two kinds of in equivalent sites in this lattice, examining the magnetization process; particular attention are focused on the one-third height of the saturation. We find that a quantum phase transition occurs at a specific value of the ratio and that a magnetization plateau appears in the vicinity of the transition.