title: Half-Quantum Vortices in an Antiferromagnetic Spinor Bose-Einstein Condensate.
abstract: We report on the observation of half-quantum vortices (HQVs) in the easy-plane polar phase of an antiferromagnetic spinor Bose-Einstein condensate. Using in situ magnetization-sensitive imaging, we observe that pairs of HQVs with opposite core magnetization are generated when singly charged quantum vortices are injected into the condensate. The dynamics of HQV pair formation is characterized by measuring the temporal evolutions of the pair separation distance and the core magnetization, which reveals the short-range nature of the repulsive interactions between the HQVs. We find that spin fluctuations arising from thermal population of transverse magnon excitations do not significantly affect the HQV pair formation dynamics. Our results demonstrate the instability of a singly charged vortex in the antiferromagnetic spinor condensate.
authors.affiliation: Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: Sang Won
authors.initials: SW
authors.lastname: Seo
authors.affiliation: Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: Seji
authors.initials: S
authors.lastname: Kang
authors.affiliation: Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Kwon
authors.affiliation: Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747, Korea.
authors.forename: Yong-il
authors.initials: YI
authors.lastname: Shin