Singular Continuous and Nonreciprocal Phonons in Quasicrystal AlPdMn

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid State Physics

Background:

• Quasicrystals possess ordered, aperiodic structures lacking translational symmetry.
• Understanding phonon propagation in these unique lattices is crucial but remains challenging.

Purpose of the Study:

• To investigate acoustic phonon modes in icosahedral quasicrystals.
• To elucidate the nature of phonon propagation in aperiodic lattices.

Main Methods:

• Inelastic neutron scattering (INS) was employed.
• The study focused on the icosahedral quasicrystal AlPdMn.

Main Results:

• A hierarchical pseudo-gap structure was observed in low-energy acoustic modes.
• Phonon intensities exhibited asymmetry concerning Bragg peaks in both energy and wave vectors.
• This asymmetry indicates nonreciprocal phonon propagation.

Conclusions:

• The findings demonstrate characteristic nonreciprocal phonon propagation in quasicrystals.
• The observed pseudo-gap structure offers new insights into lattice dynamics in aperiodic materials.