Temperature dependence of the spin polarization of a quantum Hall ferromagnet

The absolute spin polarization of a two-dimensional electron gas has been measured as a function of temperature at the $\nu =1\mathrm{}$ quantum Hall state by magnetoabsorption spectroscopy. We find that the electrons become fully polarized as $T\to 0$ and that the loss of spin polarization over the temperature regime of 500 mK to 12 K is consistent with a recently proposed continuum quantum ferromagnet model of the spin thermodynamics of the $\nu =1\mathrm{}$ quantum Hall effect state.