Giant Strain Control of Antiferromagnetic Moment in Metallic FeMn by Tuning Exchange Spring Structure

Abstract

Manipulation of the antiferromagnetic moment in antiferromagnets (AFMs) is a crucial issue for developing AFM‐based spintronic devices. Lattice strain is an effective strategy to modulate the antiferromagnetic moment and is traditionally based on a direct crystalline tailoring of AFMs. A novel method for strain tuning the antiferromagnetic moment by controlling the exchange spring in the AFM, which is applicable to other conventional AFM materials, is reported. Specifically, a TiNi(Nb) shape memory alloy (SMA) is used as the substrate of Ta/NiFe/FeMn multilayers. By thermally driven inverse martensitic phase transformation in the SMA, a significant strain of 1.3% is transferred into the film, which toggles a noticeable magnetic moment rotation of NiFe by nearly 90° in the film plane, resulting in a consequent twirling of the Néel vector of FeMn due to interfacial exchange interaction. In turn, the antiferromagnetic moment of FeMn is tailorable by tuning the exchange spring. Simultaneously, the exchange bias field is tuned significantly with a maximal variation of 350% due to the twist of the antiferromagnetic moment, which facilitates strain‐assisted magnetization reversal for developing a logic memory device. These findings provide an alternative strategy to advance the development of an AFM‐based memorizer by temperature‐driven strain engineering.

Complex Study of Magnetization Reversal Mechanisms of FeNi/FeMn Bilayers Depending on Growth Conditions

“…This effect was explained by the appearance of the AFM domain walls parallel to the interface. In addition, the observed features can be useful for developing novel methods [ 44 ] for tuning the exchange spring in the AFM.…”

A Spin‐Orbit Torque Ratchet at Ferromagnet/Antiferromagnet Interface via Exchange Spring

“…Researchers have demonstrated that AFM order exchange‐coupled to an FM can be magnetically controlled via the exchange spring effect at the AFM/FM interface. [ 26–30 ] This phenomenon has been explored in tunneling anisotropic magneto‐resistance (MR) devices [ 31–34 ] , in which the binary state of AFM switches as a function of magnetization in the adjacent FM layer. [ 34 ] This issue is of importance for AFM/FM‐based SOT devices, due to the fact that AFM order at the interface could be modified electrically via SOT.…”

Field‐Free Manipulation of Skyrmion Creation and Annihilation by Tunable Strain Engineering

“…[24,25] Moreover, Young's moduli of common metallic SMA are comparable with that of the magnetic films, facilitating effective strain transfer in tuning the electronic structure of the film significantly. [26,27] In this study, we successfully realized strainmanipulated creation and annihilation of skyrmions in [Pt/Co/ Ta] n multilayers by temperature control of the phase transition in a TiNiNb-SMA substrate. The strain effectively promoted the creation of skyrmion by lowering the nucleation field from 400 Oe to zero.…”