Heavy Fermion Behavior in the New Antiferromagnetic Compound UIr4Al15

Abstract

We report the synthesis, crystal structure, and physical properties on the new compound UIr4Al15 which crystallizes with the NdRh4Al15.4 structure type in the tetragonal space group P42/nmc. From single crystal X-ray diffraction, the compound was found to have unit cell parameters a = b = 9.0239(6) Å and c = 15.513(2) Å. The compound has been synthesized from the flux growth method using an excess of Al metal. UIr4Al15 undergoes antiferromagnetic order at approximately 20 K which is consistent with kinklike features in both electrical resistivity and specific heat measurements. Electrical resistivity under hydrostatic pressure shows that the antiferromagnetic ordering temperature is slightly shifted to higher temperatures which is suggestive of the very little pressure dependence and the localized nature of the U 5f electrons. Electronic structure calculations indicated that the Fermi surface of UIr4Al15 was quasi two-dimensional.