Random Dilution at Marginal Dimensionality in LiTb_{p}Y_{1-p}F_{4}

The $T_c\mathrm{}\left(p\right)\mathrm{}$ vs $p$ phase diagram and the critical behavior of the magnetic susceptibility of the randomly diluted, three-dimensional, Ising, dipolar-coupled ferromagnet $\mathrm{Li}{\mathrm{Tb}}_p{\mathrm{Y}}_{1-p}{\mathrm{F}}_4$ has been measured for $0.97>~p>~0.46$. For $p>~0.46$ the $T_c\mathrm{}\left(p\right)\mathrm{}$ phase diagram obeys the relation $T_c\mathrm{}\left(p\right)=2.88\mathrm{} \mathrm{K}-(3.24\mathrm{}\pm 0.10 \mathrm{K})(1-p)\mathrm{}$. At small $p$, a power-law fit is found to be qualitatively more in agreement with the data than either the renormalization-group logarithmically corrected power law or a recent prediction for the random dipolar Ising magnet.