Model for exchange bias in polycrystalline ferromagnet-antiferromagnet bilayers

Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

“…Unidirectional anisotropy models the exchange bias. Uniaxial anisotropy is a combination of shape anisotropy, crystalline anisotropy of NiFe and some uniaxial anisotropy due to the exchange bias [35]. The contribution of each of these towards the cumulative uniaxial anisotropy can vary depending on the dimensions of the bar and the thickness of the IrMn layer, however, we find that for our samples the uniaxial anisotropy is dominated by the shape anisotropy.…”

“…It is clearly associated with the exchange-coupled NiFe/IrMn interface. The two leading anisotropies commonly used to characterize FM/AFM interfaces are the exchange bias field and the rotational anisotropy, the latter being the origin of the increased coercivity [35,36]. Rotational anisotropy can be modelled as an additional effective field along the magnetization direction, and thus results in an overall decrease of the resonance field in FMR measurements.…”

“…Rotational anisotropy is due to the partially stable grains of the polycrystalline IrMn coupling to the NiFe at the interface. These are the same AFM grains responsible for the increased coercivity of magnetic hysteresis measurements [35]. This anisotropy is modeled as an additional isotropic in-plane effective field H rot along the NiFe magnetizatoin direction.…”

Determination of the Fe magnetic anisotropies and the CoO frozen spins in epitaxial CoO/Fe/Ag(001)

“…Early theories were aimed to single out the physical origin of the exchange bias by using over simplified AFM spin structures [4,5,6,7]. These models were soon replaced by more sophisticate models which are believed to better represent realistic experimental systems [8,9,10]. In experiment, most of the early measurements are on the FM layer hysteresis loops to study the pinning effect [11,12,13], training effect [14,15,16], and the finite size effect [17,18], etc.…”

Chirality Switching and Winding or Unwinding of the Antiferromagnetic NiO Domain Walls inFe/NiO/Fe/CoO/Ag(001)

“…Moreover, Koon showed that perpendicular FM/AFM interfacial magnetic coupling should be present even for a perfectly compensated AFM interface [5] though this coupling might not be responsible for exchange bias [ 6 ]. Further studies on FM/AFM interfacial coupling are more or less model dependent and aim to address specific AFM spin configurations to generating the exchange bias [7,8,9]. Different from the above approach which focuses on the interfacial FM/AFM coupling, Mauri et al considered the formation of an AFM planar domain wall in response to the FM magnetization reversal [10].…”