Quantum $s=\frac{1}{2}$ antiferromagnets on Archimedean lattices: The route from semiclassical magnetic order to nonmagnetic quantum states

We investigate the ground states of $s=1/2$ Heisenberg antiferromagnets on the 11 two-dimensional (2D) Archimedean lattices by using the coupled-cluster method. Magnetic interactions and quantum fluctuations play against each other subtly in 2D quantum magnets and the magnetic ordering is thus sensitive to the features of lattice topology. Archimedean lattices are those lattices that have 2D arrangements of regular polygons and they often build the underlying magnetic lattices of insulating quasi-two-dimensional quantum magnetic materials. Hence they allow a systematic study of the relationship between lattice topology and magnetic ordering. We find that the Archimedean lattices fall into three groups: those with semiclassical magnetic ground-state long-range order, those with a magnetically disordered (cooperative quantum paramagnetic) ground state, and those with a fragile magnetic order. The most relevant parameters affecting the magnetic ordering are the coordination number and the degree of frustration present.

Figure 1

The 11 Archimedean lattices.

Figure 2

Sketch of semiclassical magnetic order and quantum magnetic disorder of the ALs in a parameter space spanned by frustration (classical GS energy per bond; see Ref. [68] and main text) and coordination number $z$.