Control of magnetoelastic coupling in Ni/Fe multilayers using He+ ion irradiation

Abstract

This study reports the effects of post-growth He+ irradiation on the magneto-elastic properties of a Ni/Fe multi-layered stack. The progressive intermixing caused by He+ irradiation at the interfaces of the multilayer allows us to tune the saturation magnetostriction value with increasing He+ fluences and even to induce a reversal of the sign of the magnetostrictive effect. Additionally, the critical fluence at which the absolute value of the magnetostriction is dramatically reduced is identified. Therefore, insensitivity to strain of the magnetic stack is nearly reached, as required for many applications. All the above-mentioned effects are attributed to the combination of the negative saturation magnetostriction of sputtered Ni and Fe layers and the positive magnetostriction of the Ni xFe1− x alloy at the intermixed interfaces, whose contribution is gradually increased with irradiation. Importantly, the irradiation does not alter the layer polycrystalline structure, confirming that post-growth He+ ion irradiation is an excellent tool to tune the magneto-elastic properties of multilayer samples. An alternative class of spintronic devices can be envisioned with a material treatment able to arbitrary change the magnetostriction with ion-induced “magnetic patterning.”

Optimization of Permalloy properties for magnetic field sensors using He$^+$ irradiation

“…The major effect of room temperature irradiation has been shown to be improved material uniformity 39 and interface intermixing 17 . In the same way, thermal annealing is widely used to induce crystallization 40 and promote atomic diffusion 41 .…”

“…It is well known that ion irradiation is an excellent tool to tune locally the magnetic and structural properties of thin films through ordering [13][14][15][16] and interface intermixing [17][18][19][20] . In Permalloy films, ion irradiation has been shown to change the magnetic anisotropy [21][22][23] and the magneto-resistive response in the presence of exchange bias 4,24 .…”

“…However, most of these works use ion implantation [25][26][27] or heavy ions 28 , which can result in significant damage to the sample. This can be avoided by using lighter ions -like He + -with energies in the range of 10-30 keV 17,29 . In this way, collision cascades are absent and the structural modifications are confined to the vicinity of the ion path in a metal.…”

Generation of imprinted strain gradients for spintronics

“…However, the online version of record will be different from this version once it has been copyedited and typeset. PLEASE CITE THIS ARTICLE AS DOI: 10.1063/5.0157687 below saturation 19,34 . Comparing the anisotropy in the proximity and far away from the openings allows for the estimation of the changes in K ME between the two areas [35][36][37] .…”

Magnon-lattice propagation in a Morse chain: the role played by the spin-lattice interaction and the initial condition

“…The magnon dynamics under the effect of magnetoelastic coupling has attracted a high interest Masciocchi et al (2022), Chen et al (2023), Luo et al (2023), Gries et al (2022), Cong et al (2022), Challali et al (2023), Sun et al (2022), Holanda et al (2018, Xiong et al (2017), Li et al (2020, Hayashi & Ando (2018), Weiler et al (2012), Zhang et al (2019Zhang et al ( , 2020, Sasaki et al (2021), Mingran et al (2020), Morais et al (2021), Sales et al (2018Sales et al ( , 2023. In Chen et al (2023), the authors investigate the magnon propagation using a Boltzmann method framework which includes magnon-phonon interaction and diverse scattering terms.…”