Tailoring exchange bias in ferro/antiferromagnetic FePt₃ bilayers created by He⁺ beams

Abstract

We report on artificial exchange bias created in a continuous epitaxial FePt film by introducing chemical disorder using a He beam, which features tailorable exchange bias strength through post-irradiation annealing. By design, the ferromagnetic (FM)/antiferromagnetic (AF) heterostructure exhibits stratified degrees of chemical order; however, the chemical composition and stoichiometry are invariant throughout the film volume. This uniquely allows for a consideration purely of the magnetic exchange across the FM/AF interface without the added hindrance of structural boundary parameters which inherently affect exchange bias quality. Annealing at 840 K results in the strongest exchange biased system, which displays a cross-sectional morphology of fine (<10 nm) domain structure composed of both of chemically ordered and chemically disordered domains. A magnetic model developed from fitting the characteristic polarised neutron reflectometry spectral features reveals that dual interactions can be attributed to the observed exchange bias: magnetic coupling at the FM/AF interface and also between neighbouring FM (chemically disordered) and AF (chemically ordered) domains within the nominally FM layer. Our results indicate that exchange bias is hindered at interfaces which are both chemically and magnetically perfect, while annealing can be used to balance the volume proportions of interfacial FM and AF domains to enhance the magnetic interface roughness for customisable exchange bias in mono-stoichiometric FM/AF heterostructures crafted by ion beams.

Polarized Raman Spectra and Complex Raman Tensors of Antiferromagnetic Semiconductor CrPS4

“…14 Exhibiting exotic magnetism and unconventional superconductivity, 15 lowdimensional antiferromagnetic (AFM) materials are also of great importance and require extensive research. Moreover, the heterostructures of 2D ferromagnets and antiferromagnets can not only be crucial in resolving the controversy 16 regarding the mechanism of the exchange bias effect 17 but may also lead to novel findings and applications. Ternary transition metal chalcogenides (TTMCs) are promising candidates for 2D magnetism because of their diverse compositional and structural possibilities.…”

Controlled synthesis of Fe–Pt nanoalloys using atomic layer deposition

“…Ordered FePt 3 is antiferromagnetic (AFM) in nature, which can be converted into a ferromagnetic (FM) disordered state, for example by ion-beam irradiation [16,17]. This property makes it an interesting candidate for application in AFM/FM interface devices [17][18][19]. They are also proven to be excellent candidates as highly durable electrocatalysts for the oxygen reduction reaction [3,4].…”

“…They are also proven to be excellent candidates as highly durable electrocatalysts for the oxygen reduction reaction [3,4]. They have been synthesized by employing different methods such as sol-gel [13], solvothermal [3], co-precipitation [4], and sputtering [17].…”

The magnetic interfacial properties of an exchange biased nanocrystalline Ni80Fe20/α-Fe2O3 bilayer studied by polarized neutron reflectometry and Monte Carlo simulation

“…In recent years, ion-beam engineering has proven a highly efficient method for inducing nanometer-precise chemical and magnetic modifications in a wide class of materials. [2][3][4][5][6][7][8][9] Magnetic multilayers often employ the phenomenon of exchange bias by utilizing the competing magnetic interactions between neighboring ferromagnetic (FM) and antiferromagnetic (AF) nanocrystalline layers. An exchange biased state is induced when the magnetization of the FM layer becomes pinned through magnetic interactions at the chemical interface to the AF layer, if the temperature of the system is cooled below the transition temperature of the AF component.…”