TY - JOUR T1 - Spatial separation in a thermal mixture of ultracold $^174$Yb and $^87$Rb atoms JF - Physical Review A Y1 - 2011 A1 - Florian Baumer A1 - Frank Münchow A1 - Axel Görlitz A1 - Stephen E. Maxwell A1 - Paul S. Julienne A1 - Eite Tiesinga AB - We report on the observation of unusually strong interactions in a thermal mixture of ultracold atoms which cause a significant modification of the spatial distribution. A mixture of $^{87}$Rb and $^{174}$Yb with a temperature of a few $\mu$K is prepared in a hybrid trap consisting of a bichromatic optical potential superimposed on a magnetic trap. For suitable trap parameters and temperatures, a spatial separation of the two species is observed. We infer that the separation is driven by a large interaction strength between $^{174}$Yb and $^{87}$Rb accompanied by a large three-body recombination rate. Based on this assumption we have developed a diffusion model which reproduces our observations. VL - 83 UR - http://arxiv.org/abs/1104.1722v1 CP - 4 J1 - Phys. Rev. A U5 - 10.1103/PhysRevA.83.040702 ER -