 Carrier density from spin-degenerate quantum oscillations

One resolved spin branch of a two-dimensional Landau level has degeneracy $eB/h$ per area. Thus the total carrier density is $n_s=\nu eB/h$, where the filling factor $\nu$ counts all occupied spin and other internal branches, including partial filling. If consecutive unsplit orbital peaks change filling by an unresolved degeneracy $g_d$,For only spin degeneracy, $g_d=2$. Once spin splitting is resolved, adjacent individual branches differ by one rather than two; counting split subpeaks as unsplit orbital peaks gives a factor-two error.