Hall hysteresis loops in the vicinity of compensation temperature in amorphous HoCo films

Abstract

Studies of the anomalous Hall hysteresis loop in the vicinity of Tcomp are carried out to explain whether or not it is caused by the composition gradient across the thickness in amorphous flash evaporated HoCo films. Domain structure appear, when they are magnetized reversal, in the inner as well as in the outer loops. It rather shakes the correctness of Esho's model which is based on the existence of composition gradient in these films. However, regions of composition inhomogeneties which could explain the anomalous behaviour of the hysteresis loop near Tcomp are not observed.

X-ray magnetic linear dichroism as a probe for non-collinear magnetic state in ferrimagnetic single layer exchange bias systems

“…The complex physics near the compensation temperature is enriched by one more fascinating effect. Anomalous magnetic behavior in form of wing shape hysteresis loop has been reported in several RE-TM ferrimagnetic alloys that exhibit a perpendicular magnetic anisotropy such as, GdCo [20], HoCo [21], TbFe [22], GdFe [23],DyCo 4 [24], and GdFeCo [25,26,27] thin films. When applying a magnetic field perpendicular to the sample, it is expected that the net magnetization will naturally align with the external field.…”

“…According to these assumptions, a compensation temperatures range will occur and, as a result the magnetic hysteresis loop will reflect the relative weight of the corresponding "below" and "above" compensation parts of the film [20,25]. These early models have been addressed critically in relation to similar observations in HoCo films [21], questioning the original proposals based on the structural or magnetic inhomogeneities. Recently, the observation of similar anomalous loops in GdFeCo was observed to occur at faster time scales [23].…”