Temperature dependence of exchange bias in NiFe/FeMn bilayers

Abstract

Ferromagnetic resonance ͑FMR͒ and dc-magnetometry measurements were used to investigate the temperature dependence of the anisotropies responsible for the exchange-bias coupling in NiFe/FeMn bilayer. At room temperature, both measurements showed the same exchange-bias angular distributions due to a low coupling strength, H E , with respect to the antiferromagnet domain-wall formation anisotropy. The anisotropies derived from both techniques displayed identical H E values but different uniaxial anisotropies. This disagreement may be ascribed to different stabilities of antiferromagnetic grains in both techniques. At low temperature, strong disagreements were found on the exchange-bias values. They are explained by the occurrence of the slow relaxer mechanism in FMR experiments.

Temperature dependence of exchange bias in (NiFe/IrMn)n multilayer films studied through static and dynamic techniques

“…Of the suggested models, this seems to give the best fit, supporting the theory of slow relaxation by paramagnetic ions as suggested by others. [13][14][15] This model is consistent with that used in Refs. 14 and 15.…”

“…14,18 FMR shows a gradual decrease in H EB after reaching some peak value, the most obvious peak observed in the sample with the most layer repetitions. The difference in H EB determined through static and dynamic techniques can be explained based on the results of Gloanec et al 14,15 Another feature of the FMR measurements is an increase of the linewidth (∆H) as temperature decreases, leading to a broad peak which occurs for both 0 • and 180 • , as seen in Fig. 3.…”

“…Others have suggested that the impurities are paramagnetic ions present at the interface of the ferromagnetic and antiferromagnetic layers. [13][14][15] In this work, the theory of paramagnetic ion relaxation is used to describe experimental observations. according to the number of layers to hold the total sample thickness constant.…”

Magneto-Seebeck effect in spin valves

“…Higher temperature usually results in higher switching probability in the same field due to higher thermal perturbation as reported in Ref. [16,17].…”

Exchange Coupled NiFe/NiMn Bilayer Studied by a Vector Network Analyzer Ferromagnetic Resonance

“…Films with FM/AFM interfaces may be also attractive for microwave devices, because of the observed upward frequency shift [3,4]. In the second aspect, some of important issues concerning magnetization dynamics of an FM layer exchange coupled to AFM are not fully understood [5] including rotatable anisotropy that describes an enhancement of the coercive eld for magnetization reversal measurements and a negative line shift in ferromagnetic resonance (FMR) measurements [6].…”