Energy scales in the possible multiple-q phase of antlerite

The crystal structure of the natural mineral antlerite is built up from ribbons of copper atoms, where the copper atoms are arranged in a three-leg ladder with triangular rungs instead of square. This structure is extremely rare, and it is not yet known what unusual forms of magnetism it can lead to. The magnetic moments on the central leg have been reported to do nothing magnetically, but we have found that this is incorrect. We actually find at least four different types of magnetic order as we change the temperature, including a very complicated one that we do not fully understand. We need to know the energy scales of the various types of magnetic order in order to plan further work.