Strain-driven fractional spontaneous exchange bias in ferromagnetic/antiferromagnetic thin films with composition-graded ferromagnetic layer

Abstract

We experimentally demonstrate that the stress-induced magnetic anisotropy in composition-graded ferromagnetic NiFeTa layers can be employed to trigger exchange bias in NiFeTa/IrMn bilayers without using any deposition field or field cooling procedure. In particular, we found that the NiFeTa/IrMn bilayers exhibit double-shifted loops being composed of both negative and positive exchange biases when the deposition angle is low. As the deposition angle is increased, the magnetization curves change into a single-shifted loop with spontaneous exchange bias aligned along negative or positive direction. The results can be explained by the formation of magnetic domain state under the presence of a strong stress-induced magnetic anisotropy and this domain state is pinned upon the deposition of an antiferromagnetic layer. We also studied the dynamic permeability spectra of the films with respect to temperature and discussed the results in relation with the static magnetic properties.

Origin and properties of an unexpected exchange bias of Ta/Ni80Fe20/Ir20Mn80/Ta heterostructure in ultrathin limit: Impact of the oblique deposition and Ta/Ni80Fe20 alloying

“…It can also be recalled that the offset of the hysteresis loops (anomalous shift) in Fig. 3 set without any field applied during the multilayer growth or any FC protocol applied posteriorly after the sample preparation may have its origin in this hardening of the FM layer, as it was observed in literature [63] where an exchange bias was set by only the stress-induced effect in a NiFeTa/IrMn system with a laterally composition-graded 150 nm ticker NiFeTa layer. From the magnetic behavior of the top Py sublayer observed in Fig.…”

EDTA-assisted hydrothermal synthesis and magnetic properties of urchin-like YbMn2O5 microspheres

“…Furthermore, the presence of the microscopic unidirectional exchange anisotropy interaction at the FM/AFM interface is responsible for the exchange bias [41]. Phuoc et al [42,43] have found that the onset of dynamic magnetic anisotropy occurs at the AF thickness of 2 nm, lower than critical AF thickness for the onset of static magnetic anisotropy and exchange bias. Therefore, we believe that in our work the exchange bias is due mainly to the contribution of exchange coupling and anisotropy.…”