Physics (Internal)

Frustrated, degenerate, and breaking apart: the Bright Side of Life in triangular lattice

This event is part of the Condensed Matter Theory Seminar Series.

Abstract:

An evidence will be presented that despite some seemingly negative
connotation of the words in the title, the life of spin excitations in
frustrated quantum magnets is very interesting.
We demonstrate that the spin-wave excitations in a wide class of
frustrated antiferromagnets are unstable with respect to
spontaneous two-magnon decays leading to the overdamped spectra.
Their spectra also exhibit threshold singularities which lead to strong
enhancement of the decay rates along special contours in the momentum
space. Such singularities can serve as fingerprints of magnon decays,
which should help future experiments to distinguish the decay-induced
spin-wave broadening from the other scenarios that may yield broad spectra
of spin excitations.