Galvanomagnetic effects in amorphous film alloys

Measurements of the spontaneous Hall effect and magnetization of a series of rare earth-transition metal amorphous film alloys fit a model that the Hall asymmetric scattering is simply the sum of the Hall angles of the alloy components. Alloys of the form Gd
.2
(TM)
.8
where TM is Mn, Fe, Co or Ni show a maximum of
\rho_{H}/\rho
the Hall angle, (where ρ
H
is the Hall resistivity and ρ the sample resistivity) for Gd
.2
(TM)
.8
of 6%. We find that other rare earth elements have lower
\rho_{H}/\rho
ratios than Gd and that Nd-Fe alloys exhibit a smaller
\rho_{H}/\rho
than Gd-Fe because the Nd moments are in an disordered state. Of the alloys studied Gd
.2
(TM)
.8
is suitable for a Hall sensor because R
s
the spontaneous Hall coefficient (
\rho_{H} = R_{s}4\piM
) is also large, approximately 10
^-2
μΩcm/G. This is because Gd
.2
Fe
.8
is a nearly compensated ferrimagnet and
4\piM
is low. The anisotropic magnetoresistance in rare earth-transition metal alloys is about 0.1 to 0.2% and does not scale with ρ. The Corbino disc type magnetoresistance is found to be smaller than expected because in the demagnetized state magnetic domains remain effective Hall scatterers.