Phase diagram and thermal expansion measurements on the system URu2-xFexSi2.

Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URuFeSi single crystals for various values of Fe concentration x in both the hidden-order (HO) and large-moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. The uniaxial pressure derivatives of the HO/LMAFM transition temperature T change dramatically when crossing from the HO to the LMAFM phase.