Variation of blocking temperatures for exchange biased CoO/Co/Ge(100) films

Abstract

Variations of the blocking temperature and related structures for CoO/Co/Ge(100) films are investigated by employing reflection high energy electron diffraction, Auger electron spectroscopy, and surface magneto-optic Kerr effect measurements. By increasing the CoO thickness, the blocking temperature is smaller than the Neel temperature of CoO. The monotonous increase of the blocking temperature is mainly attributed to the increasing thermal stability of the antiferromagnetic grains by way of increasing the antiferromagnetic thickness. The deviation of the blocking temperature from the linear relation and the full widths at half maximum of the diffraction spots show a similar trend. The minimums appear around 25 monolayer of CoO and are related to the formation of larger grains.

Exchange Bias Effect in Ferro-/Antiferromagnetic van der Waals Heterostructures

“…Generally, the exchange bias effect strongly depends on temperature because exchange coupling between moments of the FM and AFM exists only below T B above which H EB vanishes. , Next, to examine the effect of AFM ordering on the EB, we thus performed anomalous Hall measurements at various temperatures on the four types of AFM materials exhibiting different ordering (CPS-Ising; FPS, Ising; NPS, XY; MPS, Heisenberg) as shown in Figure . The results of these measurements revealed unambiguous evidence of an EB effect in FGT/CPS, FGT/FPS devices with a clear temperature dependence.…”

Temperature-dependent magnetization reversal in exchange bias NiFe/IrMn/NiFe structures

“…Such a behavior has been found to depend on the bottom FM-layer thickness of FM/AFM/FM trilayer systems and is related to the amount of FM-layer spins that are strongly coupled with the AFM. Concerning the blocking temperature of exchange bias (the temperature at which the exchange bias becomes nonzero), it was reported in [27] that this temperature decreases with decreasing antiferromagnetic layer thickness in both NiFe/IrMn and IrMn/NiFe structures, as well as the same dependence was observed for different CoO layer thicknesses in CoO/Co/Ge films [28]. In [25], it has been shown that as temperature changes, the domain structure of NiFe/IrMn, in particular the size of domain walls, also changes affecting the exchange bias.…”