Phase diagram of diluted Ising ferromagnet LiHo$_x$Y$_{1-x}$F$_4$
  We present a systematic study of the phase diagram of LiHo$_x$Y$_{1-x}$F$_4$ ($0.25<x<1$) Ising ferromagnets obtained from neutron scattering measurements and mean-field calculations. We show that while the thermal phase transition decreases linearly with dilution, as predicted by mean-field theory, the critical transverse field at the quantum critical point is suppressed much faster. This behavior is related to competition between off-diagonal dipolar coupling and quantum fluctuations that are tuned by doping and applied field, respectively. In this paper, we quantify the deviation of the experimental results from mean-field predictions, with the aim that this analysis can be used in future theoretical efforts towards a quantitative description. 
P. Babkevich, N. Nikseresht, I. Kovacevic, J. O. Piatek, B. Dalla   Piazza, C. Kraemer, K. W. Kr\"amer, K. Proke\v{s}, S. Ma...
cond-mat.str-el