Anomalous vibration dynamics in Zn11Mg2

  • 15
  • Jun
  • 2011

We have extensively studied Mg2Zn11, a compound which shows interesting vibrational properties and exhibits intermediate structural complexity in between the Laves phase MgZn2 and alloys of higher complexity or quasicrystals .

The structure can be described as a cubic packing of a triacontahedron whose center is partially occupied by a Zn atom. This partially occupied site turned out to play a major role in understanding the lattice dynamics. The density of states shows execptionally low energy modes and a van-Hove singularity at about 4 meV,  which is unique for a close packed intermetallic compounds. Those experimental results have been simulated using ab-initio and EAM potentials. This allowed to analyze the vibrational modes in this moderately complex structure.

H. Euchner,  M. Mihalkoviˇc, F. Gaehler, M. R. Johnson, H. Schober, S. Rols, E. Suard, A. Bosak, S. Ohhashi,
A.-P. Tsai, S. Lidin, C. Pay Gomez, J. Custers, S. Paschen, and M. de Boissieu
Phys. Rev B. 83, 144202, (2011)