Large spin relaxation rates in trapped submerged-shell atoms

摘要: Spin relaxation due to atom--atom collisions is measured for magnetically trapped erbium and thulium atoms at a temperature near 500 mK. The rate constants Er--Er Tm--Tm are $3.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ $1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ cm${}^{3}$ ${\mathrm{s}}^{\ensuremath{-}1}$, respectively, $2--3$ orders of magnitude larger than those observed highly magnetic $S$-state atoms. This strong evidence an additional, dominant, spin mechanism, electronic interaction anisotropy, in between these ``submerged-shell,'' $L\ensuremath{\ne}0$ These large rates imply that evaporative cooling trap will be inefficient.