Critical magnetization behavior of the triangular- and kagome-lattice quantum antiferromagnets

We investigate S = 1/2 quantum spin antiferromagnets on the triangular and Kagome lattices in a magnetic field, using the numerical exact diagonalization. We focus particularly on an anomalous magnetization behavior of each system at one-third the saturation magnetization. Critical exponent analyses suggest that it is a conventional magnetization plateau on the triangular lattice, while an unconventional phenomenon, called the magnetization ramp, occurs on the Kagome lattice.