Speaker
Dr. Konstantinos Sfetsos
School of Physics, N.K.U.A
Wednesday, 11 March 2026 at 12:15
Auditorium A31, Faculty of Sciences bldg.
Abstract:
Spontaneous symmetry breaking in conventional ferromagnets is associated with strongly interacting spin degrees of freedom, an underlying SU(2) symmetry, and a second-order phase transition at the Curie temperature. A natural extension is to consider ferromagnets whose symmetry group is enlarged to SU(N), with N = 3, 4, …, so that the internal degrees of freedom are described by more general SU(N) representations rather than ordinary spin.
This generalization leads to a qualitatively richer phase structure. In addition to non-Abelian symmetry breaking, one may also encounter breaking of discrete conjugation symmetry, as well as the emergence of new metastable phases that can coexist over finite temperature ranges. Unlike the conventional SU(2) case, the phase transitions are typically of first order, accompanied by latent heat and hysteresis effects as the temperature is varied – closely analogous to the behavior of supercooled water.
Our results are naturally formulated in terms of Young tableaux, which label the SU(N) representations and effectively replace the conventional spin variables. Possible experimental realizations where extended SU(N) symmetries can be engineered and controlled, are also discussed.
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