Phase diagram of the Cairo pentagonal XXZ spin-1/2 magnet under a magnetic field (1105.5671v2)

Abstract: The phase diagram of the XXZ spin-1/2 magnet, equivalent to hard-core bosons, under a staggered magnetic field and on the Cairo pentagonal lattice is computed at zero and finite temperature by using a cluster mean field theory and a stochastic series expansion quantum Monte Carlo.The complex connectivity and the frustration lead to unconventional phases such as a 1/3-ferrimagnetic plateau stabilized by quantum fluctuations as well as a 5/12-topological phase induced by a local ice-rule constraint. We also report the presence of a ferrimagnetic superfluid and its thermal melting. Finally, we discuss the ferro- and antiferro- magnetic (hopping sign) cases.