Condensed Matter Seminar - Prof. Alexander Chernyshev

Abstract:

I will discuss quantum order-by-disorder effect and will present an evidence that the non-linear terms in the anisotropic kagome-lattice antiferromagnets can yield a rare example of the ground state that is different from the one favored by thermal fluctuations. The corresponding order selection will be shown to be generated by the topologically non-trivial tunneling processes, yielding a new energy scale in the system. I will also discuss the effect of the non-linear terms in the spectra of the kagome-lattice systems and will provide an analysis of the spectral properties of realistic kagome-lattice antiferromagnets such as Fe-jarosite, for which a remarkable wipe-out effect for a significant portion of the spectrum should exist due to a resonant-like decay processes involving two flat modes. Recent result concerning the spectrum of the kagome-lattice ferromagnets will also be presented.