Ground-state phases in a system of two competing square-lattice Heisenberg antiferromagnets

Abstract

We study a two-dimensional (2D) spin-half Heisenberg model related to the quasi 2D antiferromagnets (Ba,Sr)2Cu3O4Cl2 by means of exact diagonalization and spin-wave theory. The model consists of two inequivalent interpenetrating square-lattice Heisenberg antiferromagnets A and B. While the antiferromagnetic interaction JAA within the A subsystem is strong the coupling JBB within the B subsystem is much weaker. The coupling JAB between A and B subsystems is competing giving rise for interesting frustration effects. In dependence of the strength of JAB we find a collinear Neel phase, non-collinear states with zero magnetizations as well as canted and collinear ferrimagnetic phases with non-zero magnetizations. For not too large values of frustration JAB, which correpond to the situation in (Ba,Sr)2Cu3O4Cl2, we have Neel ordering in both subsystems A and B. In the classical limit these two Neel states are decoupled. Quantum fluctuations lead to a fluctuational coupling between both subsystems ('order from disorder') and select the collinear structure. For stronger JAB we find evidence for a novel spin state with coexisting Neel ordering in the A subsystem and disorder in the B subsystem.

References in corpus (6)

• Spontaneous plaquette dimerization in the $J_1-J_2$ Heisenberg model
• New quantum phase transitions in the two-dimensional J1-J2 model
• Neutron Scattering study of Sr_2Cu_3O_4Cl_2
• Magnetic phases of the mixed-spin $J_1-J_2$ Heisenberg model on a square lattice
• Influence of quantum fluctuations on zero-temperature phase transitions between collinear and noncollinear states in frustrated spin systems
• Quantum Fluctuations in the Frustrated Antiferromagnet Sr_2Cu_3O_4Cl_2

Cited by in corpus (1)

• Neutron Scattering and magnetization studies of Ba${}_2$Cu${}_{2.95}$Co${}_{0.05}$O${}_4$Cl${}_2$: A decorated two-dimensional antiferromagnet