Anisotropy engineering using exchange bias on antidot templates

Abstract

We explore an emerging device concept based on exchange bias used in conjunction with an antidot geometry to fine tune ferromagnetic resonances. Planar cavity ferromagnetic resonance is used to study the microwave response of NiO/NiFe bilayers with antidot structuring. A large frequency asymmetry with respect to an applied magnetic field is found across a broad field range whose underlying cause is linked to the distribution of magnetic poles at the antidot surfaces. This distribution is found to be particularly sensitive to the effects of exchange bias, and robust in regards to the quality of the antidot geometry. The template based antidot geometry we study offers advantages for practical device construction, and we show that it is suitable for broadband absorption and filtering applications, allowing tunable anisotropies via interface engineering.

Competing anisotropies in exchange-biased nanostructured thin films

“…15(a), the high-frequency resonance band appears labeled as HF (11)(12)(13)(14) • . Using Mumax, we simulated a 2×2 array and applied boundary conditions to ensure the finite dimensions of the system do not affect the results.…”

“…Exchange bias can also be seen as a way to modify the dynamic response of the magnetic system, as a result of the competing unidirectional and anisotropic field distribution [12]. In particular, an asymmetric microwave response with respect to the applied field has been demonstrated to originate in the unbalanced pole distribution at the edges of the holes in the antidot lattice (ADL) [13].…”

Variation of blocking temperatures for exchange biased CoO/Co/Ge(100) films

“…EB is sensitive to AFM/FM interfacial conditions and therefore atomic-scale roughness, magnetic uncompensated AFM surface, crystallographic order, and strain effects may influence its performance. [1][2][3][4][5][6][7] For the last decade, EB has been used in commercial applications such as magnetic spin-valve sensor and magnetic random access memories. [8][9][10][11] As an example for thermally assisted-MRAM (TA-MRAM), a large exchange bias field (H E ), a reduced coercive force (H C ), and well-defined temperature variations of both characteristic fields are required.…”