We give upper bounds for the number of spin 1/2 particles that can be bound
to a nucleus of charge Z in the presence of a magnetic field B, including the
spin-field coupling. We use Lieb's strategy, which is known to yield N_c<2Z+1
for magnetic fields that go to zero at infinity, ignoring the spin-field
interaction. For particles with fermionic statistics in a homogeneous magnetic
field our upper bound has an additional term of order
Z×min(B/Z3)2/5,1+∣ln(B/Z3)∣2.Comment: LaTeX2e, 8 page