Effects of high pressure on the structural, magnetic, and transport properties of the itinerant 5 f ferromagnet U2Fe3Ge
Abstract
Crystal structure, magnetic, and transport properties of the U2Fe3Ge compound have been studied under hydrostatic pressure. U2Fe3Ge crystallizes in the hexagonal crystal structure of the Mg2Cu3Si type, an ordered variant of the MgZn2 Laves structure (C14).
The Laves phase has proven highly stable; the crystal structure is maintained up to 27 GPa, the highest applied pressure. X-ray diffraction data revealed that the c direction, where the shortest U-U bonds lie, is softer than the a direction.
The bulk modulus B-0 is similar to 100 GPa. U2Fe3Ge is an itinerant ferromagnet with the Curie temperature T-C = 55 K and the spontaneous magnetic moment M-s = 1 mu(B) per formula unit at ambient pressure.
The two parameters decrease rapidly under pressure with the rates d(ln M-s)/dp = -0.33 GPa(-1) and d(ln T-C)/dp = -0.27 GPa(-1). The extrapolation of T-C and M-s indicates that the magnetic order will be suppressed between 3 and 4 GPa.
Electrical resistivity was found to decrease gradually with increasing pressure. The data in the ferromagnetic state points to the opening of a gap in the magnon spectrum at higher pressures.
U2Fe3Ge is relatively more sensitive to pressure than isostructural UNi2.