Emergent spin-1 trimerized valence bond crystal in the spin- 12 Heisenberg model on the star lattice
Shi-Ju Ran, Wei Li, Shou-Shu Gong, Andreas Weichselbaum, Jan von Delft, Gang Su
Physical review B
We explore the frustrated spin-1/2 Heisenberg model on the star lattice with antiferromagnetic (AF) couplings inside each triangle and ferromagnetic (FM) inter-triangle couplings (J_e<0), and calculate its magnetic and thermodynamic properties. We show that the FM couplings do not sabotage the magnetic disordering of the ground state due to the frustration from the AF interactions inside each triangle, but trigger a fully gapped inversion-symmetry-breaking trimerized valence bond crystal (TVBC)
... with emergent spin-1 degrees of freedom. We discover that with strengthening J_e, the system scales exponentially, either with or without a magnetic field h: the order parameter, the five critical fields that separate the J_e-h ground-state phase diagram into six phases, and the excitation gap obtained by low-temperature specific heat, all depend exponentially on J_e. We calculate the temperature dependence of the specific heat, which can be directly compared with future experiments.