Polarity Reversal of Hall Voltage at Compensation Temperature in Amorphous RE-Ni (RE:Gd, Tb, Dy, Ho) Films with Perpendicular Magnetic Anisotropy

Various amorphous rare earth - Ni (ferrimagnetic) films were prepared, and the temperature dependences of their Hall loops studied, to elucidate the mechanism by which the Hall polarity is suddenly reversed at the compensation temperature T
_comp
. The polarity of V
_H
was found to change from positive to negative at T
_comp
in all cases, in contrast with RE-Co(Fe) films, which change from negative to positive. At temperatures below T
_comp
, where the Gd spin dominates, ρ
_H
≫ 0, lending support to the hypothesis that the transition metal spin plays a dominant role in the Hall effect mechanism in RE-TM films.