Ultrasonic study of mechanically alloyed Co40Sn60

Abstract

Ultrasonic velocity changes of mechanically alloyed Co40Sn60 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 and K̃ are determined, where n is the density of states of TLS, M and K̃ are TLS coupling constants for phonons and electrons, respectively.