Magnetization ramp of the Kagome lattice antiferromagnet

Magnetization process of the S=1/2 isotropic Heisenberg antiferromagnet on the Kagome lattice is studied. Data from numerical-diagonalization method up to 39-spin systems, are reexamined from the viewpoint of the derivative of the magnetization with respect to the magnetic field. We find that the behavior of the derivative around the 1/3 height of the magnetization saturation is quite different from the cases of typical magnetization plateaux. The magnetization process of the Kagome-lattice antiferromagnet reveals a new phenomena, which we call the ``magnetization ramp.'' We also compare it with the 1/3 magnetization plateau of the triangular antiferromagnet. \\[4pt] [1] H. Nakano and T. Sakai: J. Phys. Soc. Jpn. 79 (2010) 053707, arXiv:1004.2528.