We measure a sequence of quantum Hall-like plateaux at 1/q: 9 >= q >= 2 and p/q = 2/9 fractions in the magnetisation with increasing magnetic field in the geometrically frustrated spin system SrCu2(BO3)2. We find that the entire observed sequence of plateaux is reproduced by solving the Hofstadter problem on the system lattice when short-range repulsive interactions are included, thus providing a sterling demonstration of bosons confined by a magnetic and lattice potential mimicking fermions in the extreme quantum limit.
@article{arxiv.0707.2075,
title = {Fractalization drives crystalline states in a frustrated spin system},
author = {Suchitra E. Sebastian and N. Harrison and P. Sengupta and C. D. Batista and S. Francoual and E. Palm and T. Murphy and N. Marcano and H. A. Dabkowska and B. D. Gaulin},
journal= {arXiv preprint arXiv:0707.2075},
year = {2011}
}