Crystal structure and electronic properties of new uranium intermetallic compound UGa1.85Zr0.15

The intermetallic compound UGa1.85Zr0.15 does not crystallize in the AlB2 structure shared by UGa2 and UZr2. Instead, it forms in the same orthorhombic structure as U3Ga5 (Pu3Pd5 type), but the somewhat smaller lattice parameters reduce the unit cell volume by 2.1% with respect to U3Ga5. Basic magnetic properties, namely the ferromagnetic ground state below TC = 23 K, are similar to U3Ga5. A more detail study of magnetic properties reveals interesting metamagnetic behavior with a critical field of 2-3 T, which increases with increasing temperature. The high γ-value of 110 mJ mol−1 K−2 points to a narrow 5f band at Fermi level.