Abstract

Controlling ferromagnetic thickness (t) and properties such as saturation magnetization (M_s) and effective magnetic anisotropy constant (K_eff) has been regarded as critical for the performance of magnetic tunnel junctions (MTJs) with interfacial perpendicular magnetic anisotropy. Here, we report the effects of hybridizing a CoFeB layer with a FeNiSiB layer as part of a magnetic free layer structure. We deposited thin film stacks by magnetron sputtering on Si wafers with thermal oxides and carried out post-deposition heat treatment at 300 °C for 1 h in a vacuum under a magnetic field. We found that M_s and K_eff could be tuned by adding a layer of amorphous FeNiSiB. While the M_s and K_eff values were modified, the tunneling magnetoresistance (TMR) ratios of the MTJs were maintained, even though the CoFeB thickness was decreased by half. Moreover, an asymmetric bias voltage dependence of TMR was suppressed in the MTJs with FeNiSiB/CoFeB hybrid free layers due to improvements in the interface quality between the CoFeB/MgO interfaces.

Graphic Abstract

抽象的

控制铁磁厚度（t）和诸如饱和磁化强度（M _s）和有效磁各向异性常数（K _eff）之类的属性已被视为具有界面垂直磁各向异性的磁性隧道结（MTJs）的性能的关键。在这里，我们报告了将CoFeB层与FeNiSiB层作为磁自由层结构的一部分进行混合的效果。我们通过磁控管溅射在具有热氧化物的Si晶片上沉积薄膜叠层，并在真空中，磁场下于300°C进行沉积后热处理1 h。我们发现M _s和K _eff可以通过添加一层非晶FeNiSiB来调整。虽然修改了M _s和K _eff值，但即使CoFeB的厚度减小了一半，MTJ的隧穿磁阻（TMR）比率仍得以保持。此外，由于CoFeB / MgO界面之间界面质量的提高，在具有FeNiSiB / CoFeB杂化自由层的MTJ中，TMR的不对称偏置电压依赖性得到了抑制。

图形摘要