2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/17845We develop a theory of the half-filled Landau level which shows that it is a two-component fluid. One of the components has spin up and the other spin down so that the electron-spin resonance can occur. The 1/3 filled level is fully spin polarized one-component fluid. We calculate the spin polarization at the half-filled band as a function of temperature and compare the calculated results with the experimentally measured value. Our theory is in very good agreement with the experimental data of the polarization obtained from the ratio of the Knight shifts.7 pages TeX; Fig1,2.jpg; Fig3.jpg; Three figures in two filesMesoscale and Nanoscale PhysicsStatistical Mechanicstext