Structural study of U(Pd_1 xFe_x)₂Ge₂at high pressure

Abstract

The crystal structure of the U(Pd1−xFex)2Ge2 compounds with Fe content x = 0– 0.03 and the crystal and magnetic structure of U(Pd0.98Fe0.02)2Ge2 at high external pressures up to 4.5 GPa were studied by means of powder neutron diffraction in the temperature range 1.5–300 K. With increasing Fe content the values of the lattice parameters and interatomic distances change only slightly, but it is known from previous experiments that the magnetic structure changes drastically for x ≥ 0.015. In contrast to this, high external pressure modifies the crystal structure more significantly while the magnetic structure remains unchanged. The results obtained allow one to infer that drastic changes in the magnetic structure of the U(Pd1−xFex)2Ge2 compounds with increasing Fe content are a consequence of modification of the RKKY-type (RKKY standing for Ruderman, Kittel, Kasuya and Yosida) indirect exchange interaction due to the variation of the number of conduction electrons per U atom rather than a result of lattice contraction.