title: Self-trapping of magnon Bose-Einstein condensates in the ground state and on excited levels: from harmonic to box confinement.
abstract: Long-lived coherent spin precession of (3)He-B at low temperatures around 0.2T(c) is a manifestation of Bose-Einstein condensation of spin-wave excitations or magnons in a magnetic trap which is formed by the order-parameter texture and can be manipulated experimentally. When the number of magnons increases, the orbital texture reorients under the influence of the spin-orbit interaction and the profile of the trap gradually changes from harmonic to a square well, with walls almost impenetrable to magnons. This is the first experimental example of Bose condensation in a box. By selective rf pumping the trap can be populated with a ground-state condensate or one at any of the excited energy levels. In the latter case the ground state is simultaneously populated by relaxation from the exited level, forming a system of two coexisting condensates.
authors.affiliation: Low Temperature Laboratory, School of Science, Aalto University, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Autti
authors.forename: Yu M
authors.initials: YM
authors.lastname: Bunkov
authors.forename: V B
authors.initials: VB
authors.lastname: Eltsov
authors.forename: P J
authors.initials: PJ
authors.lastname: Heikkinen
authors.forename: J J
authors.initials: JJ
authors.lastname: Hosio
authors.forename: P
authors.initials: P
authors.lastname: Hunger
authors.forename: M
authors.initials: M
authors.lastname: Krusius
authors.forename: G E
authors.initials: GE
authors.lastname: Volovik