Low-temperature Resonant Ultrasound Spectroscopy on Alpha-Pu

We measured the elastic constants of polycrystalline Alpha-plutonium (16 atoms per unit cell) as a function of temperature (18-350K) using Resonant Ultrasound Spectroscopy$^{1}$. A smooth behavior in the temperature dependence of the elastic moduli curves is found, with no evidence for any electronic, magnetic or structural phase transitions. The data can be fit by the quasiharmonic Einstein-oscillator model. The high-temperature bulk modulus yields an anharmonic Gr\"{u}neisen parameter gamma of 5.1, and the low-temperature elastic constants results a Debye temperature $\Theta _{D}$ of about 205K$^{2}$. [1] Albert Migliori and John Sarrao, ``Resonant Ultrasound Spectroscopy,'' John Wiley {\&} Sons, INC 1997 [2] A. Migliori, H. Ledbetter, J. Betts, M. Ramos, S. Harrington, and S. El-Khatib, to be submitted to Physical Review B, 2004