Fig. 2

Formation of equilibrium spin domains without magnetic force. a–c Linear densities of each Zeeman component m_F as a function of position for increasing quadratic Zeeman energies q. Each line in the false color plots corresponds to an individual profile as shown in Fig. 1b. The arrows mark the locations of the observed q_1,exp and predicted \(q_{\mathrm{1}}^{{\mathrm{GP}}},q_{\mathrm{2}}^{{\mathrm{GP}}}\) critical quadratic Zeeman energies. d Magnetic transition for M_||/N = 0.51(3). Evolution with q of the normalized densities at the center of the trap. The gray lines show a piece-wise function constant below q_1,exp and growing as \(1 - e^{ - |q - q_{{\mathrm{1,exp}}}|/{\mathrm{\Delta }}q}\) above. We obtain the quoted experimental values of q_1,exp fitting this function to the experimental data for m_F = 0. The quoted uncertainty correspond to a 90% confidence interval assuming Gaussian noise and independent errors. The trap frequencies, magnetization, and atom number are as in Fig. 1