Exchange biasing by Ir19Mn81: Dependence on temperature, microstructure and antiferromagnetic layer thickness

Abstract

Electric field-induced magnetization reversal in a perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction Appl. Phys. Lett. 101, 122403 (2012) Spin transfer torque devices utilizing the giant spin Hall effect of tungsten Appl. Phys. Lett. 101, 122404 (2012) Modifications of magnetic anisotropy and magnetization reversal in [Co0.4nm/Pd0.7nm]50 multilayers induced by 10keV-He ion bombardment J. Appl. Phys. 112, 063901 (2012) Properties of magnetic nickel/porous-silicon composite powders AIP Advances 2, 032167 (2012) Additional information on J. Appl. Phys.We have investigated the thermal stability of the exchange biasing interaction in antiferromagnetic/ ferromagnetic bilayers of Ir 19 Mn 81 and Ni 80 Fe 20 or Co 90 Fe 10 . The exchange-biasing field and the coercive field were found to depend strongly on the thickness of the Ir 19 Mn 81 layer and on the crystallographic texture of the bilayer. The exchange-biasing field at room temperature has a maximum at 4 nm Ir 19 Mn 81 layer thickness and then decreases for increasing Ir 19 Mn 81 layer thickness. This coincides quite well with the thickness dependence of the ͑111͒ texture measured in Ir 19 Mn 81 layers. Removing the Ta seed layer resulted in the disappearance of the ͑111͒ texture and at the same time the exchange-biasing field decreased for all Ir 19 Mn 81 layer thicknesses. For films with a Ta seed layer and 8 nm Ir 19 Mn 81 or more, we have found a blocking temperature of 560 K, decreasing with decreasing Ir 19 Mn 81 layer thickness to around room temperature for 2 nm Ir 19 Mn 81 . Removing the Ta seed layer resulted in a decrease of the blocking temperature for all layer thicknesses investigated. We have concluded that the ͑111͒ texture is an important factor governing the size of the exchange-biasing field and the thermal stability.

Correlation between perpendicular exchange bias and magnetic anisotropy in IrMn∕[Co∕Pt]n and [Pt∕Co]n∕IrMn multilayers

“…These values for are about one order of magnitude smaller than those measured on IrMn exchange-biased systems with inplane magnetization. [17][18][19][20][21][22] Although rather small, the perpendicular interfacial exchange energies for the Co/ Pt-IrMn system are comparable to those measured on similar CoFe/ Pt and Co/ Pt multilayers with an AFM FeMn film on top. 9 To determine the effects of field annealing on the perpendicular magnetic anisotropy of exchange-biased Co/ Pt multilayers we measured the EHE voltage with an in-plane FIG.…”

“…For these structures, differences in ͑111͒ texture, grain size, and interface roughness have been suggested as possible explanations. [17][18][19][20][21][22] Figure 2͑c͒ shows XRD scans on Co/ Pt multilayers with IrMn on the top and IrMn at the bottom. In both cases a ͑111͒ texture is measured for the Pt and IrMn layers.…”

“…IrMn is less corroding than FeMn, and it combines a relatively high interfacial exchange energy ͑ Ϸ 0.2 mJ/ m 2 ͒ with a high blocking temperature of about 250°C. [17][18][19][20][21][22] Recently, it was shown that IrMn can be successfully used to exchange bias systems with out-of-plane magnetization. 23,24 In this paper we study perpendicular exchange bias in Co/ Pt multilayers with an IrMn film at the bottom or on top.…”

Linearization strategies for high sensitivity magnetoresistive sensors

“…However the exchange field (H exch ) of the sensing layer must be small as it will define the sensor saturation field and consequently its sensitivity. The exchange coupling strength is set by an adequate choice of antiferromagnet and adjacent ferromagnetic layer [96].…”

Influence of surface roughness and deposition order on exchange bias in bilayer structures NiFe/IrMn

“…there will be no bias. At t AF > t С , H EB grows with increasing thickness and reaches maximum at t AF = t max , and at still higher thickness H EB either saturates or decreases [12][13][14][15][16][17].…”