Spin and the Coulomb Gap in the Half-Filled Lowest Landau Level
  The Coulomb gap observed in tunneling between parallel two-dimensional electron systems, each at half filling of the lowest Landau level, is found to depend sensitively on the presence of an in-plane magnetic field. Especially at low electron density, the width of the Coulomb gap at first increases sharply with in-plane field, but then abruptly levels off. This behavior appears to coincide with the known transition from partial to complete spin polarization of the half-filled lowest Landau level. The tunneling gap therefore opens a new window onto the spin configuration of two-dimensional electron systems at high magnetic field. 
J.P. Eisenstein, T. Khaire, D. Nandi, A.D.K. Finck, L.N. Pfeiffer, and   K.W. West
cond-mat.mes-hall