arXiv:1203.6677 · Physical Review B
Quantum phase transitions in bilayer SU( N ) antiferromagnets
Ribhu K. Kaul
Abstract
We present a detailed study of the destruction of SU($N$) magnetic order in square lattice bilayer antiferromagnets using unbiased quantum Monte Carlo numerical simulations and field theoretic techniques. We study phase transitions from an SU($N$) N\'eel state into two distinct quantum disordered ``valence-bond'' phases: a valence-bond liquid (VBL) with no broken symmetries and a lattice-symmetry-breaking valence-bond solid (VBS) state. For finite interlayer coupling, the cancellation of Berry phases between the layers has dramatic consequences on the two phase transitions: the N\'eel-VBS transition is first order for all $N\ensuremath{\ge}5$ accesible in our model, whereas the N\'eel-VBL transition is continuous for $N=2$ and first order for $N\ensuremath{\ge}4$; for $N=3$ the N\'eel-VBL transition show no signs of first-order behavior.