Abstract
U(Ni,Rh)Al alloys crystallize in the hexagonal ZrNiAl structure. Here, we report on measurements on a single crystalline member of this series, namely, U Ni0.39 Rh0.61 Al. Similar to other members of this series, this compound exhibits highly anisotropic properties with the easy-magnetization direction along the c -axis. We report in the results of electrical resistance, magnetoresistance, and thermal expansion as a function of temperature (2-300 K) and applied magnetic field (0-18 T). The results provide strong evidence for antiferromagnetic ordering at TN ≤15 K followed by a ferromagneticlike (ferro-or ferrimagnetic) transition around 7 K (we use the term "ferromagneticlike" because, based on our bulk data, we cannot exclude canted moments with antiferromagnetic components or ferromagnetic order of two different moments). A magnetic B-T phase diagram for U Ni0.39 Rh0.61 Al is proposed.
| Original language | English (US) |
|---|---|
| Article number | 07B714 |
| Journal | Journal of Applied Physics |
| Volume | 103 |
| Issue number | 7 |
| DOIs | |
| State | Published - 2008 |
| Externally published | Yes |
Bibliographical note
Funding Information:Work at the Lujan Center was supported in part by the division of Basic Energy Sciences of the US Department of Energy. Work at the Pulse Field Facility, NHMFL, was performed under the auspices of the NSF, the US Department of Energy, and the State of Florida. FIG. 1. Tentative x - T magnetic phase diagram for U Ni 1 − x Rh x Al compounds (after Ref. 2 ). The closed circles correspond to proposed Néel temperatures T N , the squares correspond to proposed Curie temperatures T C , and open circles correspond to undefined type of magnetic ordering. The lines are guides to the eyes. The position of our U Ni 0.39 Rh 0.61 Al single crystal is indicated by the arrow. FIG. 2. Temperature dependence of the electrical resistivity of U Ni 0.39 Rh 0.61 Al at fixed magnetic fields applied along the c -axis. FIG. 3. Percentage change of the normalized magnetoresistance of U Ni 0.39 Rh 0.61 Al , i.e., 100 % × Δ ρ ∕ ρ ( 0 T ) = 100 % × { ρ ( B ) − ρ ( 0 T ) } ∕ ρ ( 0 T ) , as a function of field applied along the c -axis at various fixed temperatures. FIG. 4. Temperature dependence on the linear thermal expansion coefficient, α c = 1 ∕ L ( d L ∕ d T ) B ∥ c , of U Ni 0.39 Rh 0.61 Al for magnetic fields applied along the c -axis. FIG. 5. Tentative magnetic B - T phase diagram of U Ni 0.39 Rh 0.61 Al for magnetic fields applied along the c -axis. Open circles correspond to the electrical-resistivity anomalies and the solid circles are extracted from thermal expansion anomalies.