Observation of Low-Energy Einstein Phonon and Superconductivity in Single-Crystalline LaBe$_{13}$

The thermal and electrical transport properties of single-crystalline LaBe$_{13}$ have been investigated by specific-heat ($C$) and electrical-resistivity ($rho$) measurements. The specific-heat measurements in a wide temperature range revealed the presence of a hump anomaly near 40 K in the $C$($T$)/$T$ curve, indicating that LaBe$_{13}$ has a low-energy Einstein-like-phonon mode with a characteristic temperature of $sim$ 177 K. In addition, a superconducting transition was observed in the $rho$ measurements at the transition temperature of 0.53 K, which is higher than the value of 0.27 K reported previously by Bonville et al. Furthermore, an unusual $T^3$ dependence was found in $rho$($T$) below $sim$ 50 K, in contrast to the behavior expected from the electron--electron scattering or the electron--Debye phonon scattering.