Structural and dynamic origin of the boson peak in a Cu-Zr metallic glass

N Jakse and A Nassour and A Pasturel, PHYSICAL REVIEW B, 85, 174201 (2012).

DOI: 10.1103/PhysRevB.85.174201

Using molecular dynamics simulations, we studied the short-time dynamics of the amorphous Cu50Zr50 alloy. We determined the occurrence of a well- defined boson peak in agreement with experimental observations. Our results indicate that the structural origin of the boson peak can be related to Cu and Zr atoms having large mean-square amplitudes in low- density defective local structures. Moreover, we show that these structural motifs display quasilocalized modes that resonantly couple with transverse phonons, leading to the accumulation of the low-energy modes around the boson peak. Finally, the correlation between the attenuation of sound and the boson peak is discussed.

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