Field-induced disorder in a gapped spin system with non-magnetic   impurities
  We study S=1/2 dimers which are weakly coupled by three-dimensional antiferromagnetic interactions J'. It is commonly known that doping with non-magnetic impurities immediately induces a long-range Neel order. We show that application of an external magnetic field H may drive the system back to a disordered phase. We discuss the zero temperature phase diagram in the (H,J') plane and we propose suggestions for experiments. 
H.-J. Mikeska, Asimkumar Ghosh, and A. K. Kolezhuk