Self-localization of magnons and a magnetoroton in a binary Bose-Einstein condensate

Physical Review A: Atomic, Molecular, and Optical physics. 2020. Vol. 101. No. 1. P. 013621.

Andreev S. V., O.I. Utesov

We consider a two-component Bose-condensed mixture characterized by positive s-wave scattering lengths.
We assume equal densities and intraspecies interactions. By doing the Bogoliubov transformation of an effective
Hamiltonian, we obtain the lower energy magnon dispersion incorporating the superfluid entrainment between
the components. We argue that p-wave pairing of distinct bosons should be accompanied by self-localization of
magnons and formation of a magnetoroton. We demonstrate the effect on a model system of particles interacting
via step potentials.

Keywords: phase separation, Bose-Einstein condensate, magnetoroton, self-localization, Конденсат Бозе-Эйнштейна, разделение фаз, магнеторотон, автолокализация