Effect of isothermal crystallization in antiferromagnetic IrMn on the formation of spontaneous exchange bias

Abstract

Recently, a spontaneous exchange bias (SEB) driven by the isothermal crystallization of the antiferromagnetic IrMn layer has been reported in IrMn/FeCo bilayer. However, the key factors to determine the magnitude of SEB have not been clearly understood yet. Here, we investigate the effect of isothermal crystallization in IrMn layer on the formation of SEB in IrMn/CoFeB bilayer through preparing the samples with different degrees of isothermal crystallization in IrMn layer. The SEB is negligible in the sample with more structure-stable IrMn layer, confirming that the isothermal crystallization of IrMn plays a crucial role in the formation of SEB. However, the SEB field does not change significantly with the free-relaxation time of IrMn/CoFeB bilayers or IrMn layer. These results indicate that a slight degree of isothermal crystallization in IrMn layer is sufficient to induce a large SEB in IrMn/CoFeB bilayer. Our results not only confirm the newly reported SEB driven by the isothermal crystallization in IrMn layer but also clarify the key factor to control the magnitude of SEB.

Field-Free Spin–Orbit Torque-Induced Magnetization Switching in the IrMn/CoTb Bilayers with a Spontaneous In-Plane Exchange Bias

“…We deposited the multilayers of Cu(0.5)/Ir 25 Mn 75 (8)/Co 1– x Tb x (3.5)/Ta­(3) (unit in nm) on thermally oxidized Si substrates, and the film stack is depicted in Figure a. The deposition of a 0.5 nm-thick Cu layer is to offer a (111) orientation for the Ir 25 Mn 75 (IrMn) layer, which is necessary for obtaining spontaneous EB. , Note that the CoTb layer was fixed at a small thickness of 3.5 nm for acquiring significant EB and considerable current flowing through the IrMn layer as well. The optical image of a Hall-bar and schematic of an anomalous Hall effect (AHE) measurement setup are depicted in Figure b.…”

Zero-field-cooling exchange bias up to room temperature in the strained kagome antiferromagnet Mn3.1Sn0.9

“…Up to now, ZFC EB has been found in some alloys, 7–10 nitrides, 11,12 oxides, 13–17 thin films. 18,19 However, only very few materials have T B values up to room temperature. It is well known that exchange bias is an interface effect.…”

Sensitive angle-dependent magnetoelectric coupling in cluster-assembled flexible composites

“…Cluster-assembled composites have recently gained increasing attention because of their unique structural compatibility and stability [10,11]. In addition there are various other phenomena and devices related to magnetic anisotropy, but the origin is beyond the theoretical scope of crystal polycrystalline symmetry [12][13][14][15]. Thus, clarifying the origin and further obtaining high-strength magnetoelastic anisotropy are crucially important not only for the fundamental magnetism but also for the design of flexible ME composites.…”