Spontaneous magnetization and structure formation in a spin-1 ferromagnetic Bose-Einstein condensate

Lorraine E. Sadler, James Higbie, Mukund Vengalattore +2 more

A. N. Wenz, Jennie Guzman, Kater W. Murch +1 more

Hao Zhu, Sirong Lu, Xiaoyang Shi +1 more

Hiroki Saito, Masahito Ueda

Motivated by recent experiments involving the nondestructive imaging of magnetization of a spin-1 $^{87}\mathrm{Rb}$ Bose gas [J. M. Higbie et al., Phys. Rev. Lett., 95, 050401 (2005)], we address the question of how the spontaneous magnetization of a ferromagnetic Bose-Einstein condensate occurs in a spin-conserving system. Due to competition between the ferromagnetic interaction and the total spin conservation, various spin structures such as staggered magnetic domains and helical and concentric ring structures are formed, depending on the geometry of the trapping potential.

Hiroki Saito, Yuki Kawaguchi, Masahito Ueda

We study the dynamics of the quantum phase transition of a ferromagnetic spin-1 Bose-Einstein condensate (BEC) from the polar phase to the broken-axisymmetry phase by changing magnetic field, and find the spontaneous formation of spinor domain walls followed by the creation of polar-core spin vortices. We also find that the spin textures depend very sensitively on the initial noise distribution, and that an anisotropic and colored initial noise is needed to reproduce the Berkeley experiment [Sadler et al., Nature (London) 443, 312 (2006)]. The dynamics of vortex nucleation and the number of created vortices depend also on the manner in which the magnetic field is changed. We point out an analogy between the formation of spin vortices from domain walls in a spinor BEC and that of vortex-antivortex pairs from dark solitons in a scalar BEC.

Zachary Glassman, Donald P. Fahey, Ryan Wilson +2 more