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

Abstract

Perpendicular exchange bias has been observed for IrMn/ ͓Co/ Pt͔ n and ͓Pt/ Co͔ n / IrMn multilayers in the as-deposited state. The exchange bias field is largest when the IrMn film is grown on magnetically saturated Co/ Pt multilayers ͑8.12 mT for n =3͒, whereas it is considerably smaller when domain formation in the IrMn film occurs before Co/ Pt deposition ͑3.30 mT for n =3͒. After annealing at 220°C in an out-of-plane magnetic field the perpendicular exchange bias field and magnetic anisotropy are considerably larger for the Co/ Pt multilayers with an IrMn film at the bottom. The apparent correlation between bias and anisotropy is explained by the dependence of the perpendicular exchange bias field on the orientation of the Co spins near the Co/ IrMn interface.

Simulating a perpendicular exchange-biased structure with a partially covering nonmagnetic insertion at the FM/AFM interface

“…One of the most promising materials of this type is the Co/Pt multilayered system, with magnetic anisotropies that are predominantly perpendicular to the films. These FM structures, after coupling to the antiferromagnetic IrMn film, revealed a perpendicular exchange bias shift [5][6][7][8]. Similar perpendicular biasing has been observed in the FeNi/FeMn multilayers after coupling with the antiferromagnetic FeMn [9].…”

Tunneling magnetoresistance of perpendicular CoFeB-based junctions with exchange bias

“…Secondly, the stacks of the soft and pinned electrode must show high PMA to ensure that the relative orientation of the electrodes' magnetizations can be parallel (low resistance) or antiparallel (high resistance) in the perpendicular direction. Moreover, the bottom part of the junction is preferred for the pinned part, because MnIr acts as an additional seed layer that promotes the (111) texture of the subsequent ferromagnetic layer and therefore higher PMA as van Dijken et al reported 12 . Although the CoFeB/MgO films directly grown on a MnIr layer exhibit relatively high PEB, one of their major disadvantages is the insufficient PMA.…”

Temperature dependent coercivity crossover in pseudo-spin-valve magnetic tunnel junctions with perpendicular anisotropy

“…In our pMTJ stacks, the top (Co 0.4/Pt 2.0) 3 serves as the soft layer since it has a smaller H c at room temperature compared to that of the bottom (Co 0.7/Pt 2.0) 3 layer according to our previous study. 8 Under a bias voltage of 20 mV, a typical pMTJ device shows a tunnel magnetoresistance of up to 9% and 25% at room temperature and 50 K, respectively, as shown in Fig. 1.…”

“…Co/Pd, Co/Pt, Co/Au, and Co/Ni multilayers all show perpendicular anisotropy for certain ranges of thickness and period. [5][6][7][8][9] Lots of studies have been carried out on the fabrication and characterization of pMTJs with AlO x and MgO barriers. [10][11][12][13][14] Promising progress has been made not only on reaching high tunneling magnetoresistance (TMR) ratios but also achieving a low critical current density.…”