Magnetic slowing down of spin relaxation due to binary collisions of alkali-metal atoms with buffer-gas atoms.

We report the first studies of magnetic decoupling of the spin relaxation of alkali-metal atoms due to binary collisions with buffer gases. When binary collisions are the dominant relaxation mechanism, the relaxation and its magnetic decoupling are well described by the S-damping rate Gamma(SD) due to the spin-rotation interaction gammaN.S, the spin exchange rate Gamma(EX) for collisions between alkali atoms, and a new "Carver rate" Gamma(C), due to the pressure-shift interaction deltaAI.S, which can substantially broaden the magnetic decoupling curve while having no influence on the zero-field rates.