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Anomalous vibration dynamics in Zn11Mg2

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.



Publication:
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)

Figure: Inelastic neutron spectrum measured on the IN4 spectrometer of the ILL.
Figure: Inelastic neutron spectrum measured on the IN4 spectrometer of the ILL.