Quantum phase transition in the dioptase magnetic lattice C. Gros, P. Lemmens, K.-Y. Choi, G. Güntherodt, M. Baenitz and H. H. Otto Europhys. Lett., 60 2 (2002) 276-280 Published online: 01 October 2002 DOI: 10.1209/epl/i2002-00347-0