1203.6677 (Ribhu K. Kaul)

Quantum phase transitions in bilayer SU($N$) anti-ferromagnets    [PDF]

Ribhu K. Kaul

We present a detailed study of the destruction of SU($N$) magnetic order in square lattice bilayer anti-ferromagnets 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 inter-layer 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 $N$ in our model, whereas the N\'eel-VBL transition is continuous for $N=2,3$ and first order for $N\geq 4$.

View original: http://arxiv.org/abs/1203.6677