Electrical, Magnetic and Thermal Properties of UNi₂Si₂ and UNi₂Ge₂

Abstract

<p>The magnetic susceptibility, resistivity, and Hall coefficient of single crystals of UNi₂Si₂ and UNi₂Ge₂ have been investigated. Thermoelectric power and specific heat measurements of UNi₂Si₂ have also been carried out.</p> <p>The magnetic susceptibility of UNi₂Si₂ and UNi₂Ge₂ follows the Curie-Weiss law in the paramagnetic state at high temperatures and the anisotropy shows that the magnetic moments on the U atoms are constrained to lie preferentially along the c axis.</p> <p>The resistivity of these two compounds is largely due to magnetic scattering and the phonon contribution only amounts to 8-14% of the total resistivity at room temperature. Along the c axis, the resistivity shows a Kondo type of behaviour at high temperatures. The temperature dependence of the Hall coefficient can be accounted for by a theoretical model invoking a magnetic skew-scattering process. Distinct features and anomalies are observed in both the resistivity and the Hall coefficient at the magnetic transitions of these two compounds.</p> <p>The thermoelectric power of single crystal UNi₂Si₂ is also anisotropic, with the c-axis component strongly coupled to the magnetic phase transitions. The gamma value obtained from the specific heat measurements of UNi₂Si₂ is 22 mJ mol⁻¹ K⁻² which indicates a small mass enhancement in the system.</p>