Novel ferrimagnetism in quantum Heisenberg spin systems with frustration

Tokuro Shimokawa, Hiroki Nakano, Tôru Sakai

Johannes Richter, Ulrich Schollwöck, Nedko B. Ivanov

Shoji Yamamoto, Takahiro Fukui, Tôru Sakai

Tokuro Shimokawa, Hiroki Nakano

We study ground-state properties of the Heisenberg frustrated spin chain with interactions up to fourth nearest neighbors by the exact-diagonalization method and the density matrix renormalization group method. We find that ferrimagnetism is realized not only in the case of S=1/2 but also S=1 despite that there is only a single spin site in each unit cell determined from the shape of the Hamiltonian. Our numerical results suggest that a "multi-sublattice structure" is not required for the occurrence of ferrimagnetism in quantum spin systems with isotropic interactions.

Hiroki Nakano, Minoru Takahashi

Zhang Song-Jun, Jianjun Jiang, Yongjun Liu +1 more

Using density-matrix renormalization group (DMRG) method, we studied the effect of magnetic frustrations due to next-nearest- neighbor bonds in a system of quasi-one-dimensional Heisenberg antiferromagnetic chain but with ferrimagnetic properties. In this paper, the ground state energy per unit cell, spin correlation function and spin gap are calculated. As a result of the frustrations, the quantum disordered phase with the spin gap appears at the spin order-disorder phase transition point αC≈0.412 to α＝1. And in the region of magnetic-order phase, the increasing magnetic frustrations reduce the magnetic order.