Thermal properties of U 3 Al 2 Si 3 single crystal

Heat capacity data of U 3 Al 2 Si 3 single crystal exhibit a maximum at 38 K connected with a transition to a magnetically ordered state. For a full description of the electron part we used γ 0 = 145 mJ/mol K 2 and for the phonon part of the specific heat we used the harmonic approximation of the phonon spectrum including both the Debye model with T D = 296 K and the Einstein model with T E = 136, 249 and 438 K. The heat capacity data below the magnetic transition down to 2 K fit very well within the model introducing the energy gap Δ = 39 K in the dispersion relation of magnons. An upturn of the C / T ( T ) curve, found below T = 2 K, can not be fully attributed to the nuclear Schottky contribution. The electronic heat capacity coefficient ( γ ≈ 230 mJ/mol K 2 is enhanced and varies between 0.15 K and 12 K as the square root of T . (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)