Chemical pressure tuning of URu2Si2 via isoelectronic substitution of Ru with Fe

We have used specific heat and neutron diffraction measurements on single crystals of URu2-xFexSi2 for Fe concentrations x <= 0.7 to establish that chemical substitution of Ru with Fe acts as "chemical pressure" P-ch as previously proposed by Kanchanavatee et al. [Phys. Rev. B 84, 245122 ( 2011)] based on bulk measurements on polycrystalline samples. Notably, neutron diffraction reveals a sharp increase of the uranium magnetic moment at x = 0.1, reminiscent of the behavior at the "hidden order" to large-moment-antiferromagnetic phase transition observed at a pressure Px approximate to 0.5-0.7 GP(a) in URu2Si2. Using the unit-cell volume determined from our measurements and an isothermal compressibility kappa(T) = 5.2 x 10(-3) GPa(-1) for URu2Si2, we determine the chemical pressure Pch in URu2-xFexSi2 as a function of x. The resulting temperature (T)-chemical pressure ( P-ch) phase diagram for URu2-xFexSi2 is in agreement with the established temperature (T)-external pressure (P) phase diagram of URu2Si2.