||Exact Ground States of Frustrated Quantum Spin Systems Consisting of Spin-Dimer Units
Hikihara, T. ,
Tonegawa, T. ,
Okamoto, K.Sakai, T.
Journal of the Physical Society of Japan
054709-8 , 2017-05
An S = 1/2 triangular-lattice Heisenberg antiferromagnet with next-nearest-neighbor (NNN) interactions is investigated under a magnetic field by the numerical-diagonalization method. It is known that, in both cases of weak and strong NNN interactions, this system reveals a magnetization plateau at one-third of the saturated magnetization. We examine the stability of this magnetization plateau when the amplitude of NNN interactions is varied. We find that a nonplateau region appears between the plateau phases in the cases of weak and strong NNN interactions.