Spin mixing and protection of ferromagnetism in a spinor dipolar condensate

Understand

We study spin mixing dynamics in a chromium dipolar Bose-Einstein Condensate, after tilting the atomic spins by an angle $\theta$ with respect to the magnetic field.

• Spin mixing is triggered by dipolar coupling, but, once dynamics has started, it is mostly driven by contact interactions.
• For the particular case $\theta=\pi/2$, an external spin-orbit coupling term induced by a magnetic gradient is required to enable the dynamics.
• Then the initial ferromagnetic character of the gas is locally preserved, an unexpected feature that we attribute to large spin-dependent contact interactions.