
405Magnetic Nanosensors
to be low. Thus, up-spin electrons experience small resistance, the
down-spin electrons experience large resistance, and the sum-total
resistance is given by
R
R R
R R
Parallel
=
+
↑
↓
↑
↓
2
(7.4)
There are similarities between the band structure of Cu and the band struc-
ture of the majority spins in Co. This good band matching implies a high
transmission probability for the majority-spin electrons across the Co/Cu
interface. The up-spin electrons barely notice any difference in the num-
ber of electrons per atom in their journey from the ferromagnetic layer to
the nonmagnetic layer. To them, the lattice potential is smooth