Excotic ground states in the honeycomb J1-J2 Heisenberg model

Abstract

In this work, new sets of multi-q ground states of the honeycomb J1-J2 Heisenberg model in the case of J1 = 2J2 were found by rewriting the Hamil- tonian in a way that allows for a geometric interpretation of the ground states of the J1-J2 honeycomb Heisenberg model. It was then investigated whether these new obtained multi-q ground states are competitive with the spin spiral ground states favoured by quantum fluctuations in a low temperature environ- ment. This was achieved by calculating the partition function of the classical perturbations of the multi-q ground states. The numerical evaluation reveals that Coplanar states are more likely of being realized at low temperatures than non-coplanar states, and among the coplanar states, the colinear states have the highest probability of being realized at low temperatures. The most favoured co-linear ground state is also a single-q spin spiral ground state which has pre- viously been found to be the spin spiral ground state favoured by quantum fluctuations.