Quantum Correlation, Entanglement in the Two-Dimensional Heisenberg Antiferromagnetic Model on Kagome Lattice

Masaaki Nakamura, Satoshi Nishimoto

Reza Haghshenas, D. N. Sheng, Shou-Shu Gong

L.S. Lima

P. Azaria, C. Hooley, P. Lecheminant +2 more

We study a model of the spin $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ Heisenberg antiferromagnet on a one-dimensional lattice with the local symmetry of the two-dimensional Kagom\'e lattice. Using three complementary approaches, it is shown that the low-energy spectrum can be described by two critical Ising models with different velocities. One of these velocities is small, leading to a strongly localized Majorana fermion. These excitations are singlet ones, whereas the triplet sector has a spectral gap.

Katsuhiro Morita, Takami Tohyama

Magnetization plateaus in quantum spin systems emerges in two-dimensional frustrated systems such as kagome lattice. The spin-1/2 antiferromagnetic Heisenberg model on square-kagome lattice is also appropriate for the study of magnetization plateau. Motivated by recent experimental finding of such a square-kagome lattice with nonequivalent three bonds, we investigate the phase diagrams and magnetization plateaus of the lattice by the exact diagonalization method. In addition to previously reported the 1/3 and 2/3 plateaus in the model with two equivalent bonds, we find a new 2/3 plateau whose magnetic structure is characterized by spontaneously broken four-fold rotational symmetry. The plateau appears only in the case of three nonequivalent bonds. We propose the possibility of finding plateaus including the new one.

L.S. Lima