Ultrasonic velocity changes of mechanically alloyed Co40
are investigated as a function of temperature at low temperatures. It is found that the velocity increases logarithmically with temperature below ∼1 K, indicating the existence of features characteristic of the glassy state. With the two level tunneling system (TLS) model developed for amorphous materials, factors nM2
are determined, where n
is the density of states of TLS, M
are TLS coupling constants for phonons and electrons, respectively.