Spin Exchange and Magnons in Cold Atomic Hydrogen Gas

摘要: We report on an experimental study of electron spin waves (magnons) in the gas of atomic hydrogen. H atoms are stabilized with respect to their recombination by polarizing their electron spins in strong magnetic fields of 4.6 T and temperatures below 0.5 K. Using special hydraulic compression by a piston of superfluid helium we compress the gas to very high densities of the order of 5* 1018 cm-3. At these conditions, the gas is fully in a quantum regime when the thermal de-Broglie wavelength is much larger than the scattering length of atoms in binary collisions. The quantum effects related with indistinguishability of atoms start to play important role and lead to strong spin-exchange. As a result, in such spin changing collisions the spins of the atoms slightly rotate around their sum, exhibiting a phenomenon known as an Identical Spin Rotation (ISR) effect [1]. Accumulating in multiple collisions the ISR leads to a …