An unexpected twist | Nature Reviews Materials

Access through your institution Buy or subscribe Creating stable droplets in environments where they can be imaged is challenging. Past experiments used orthogonal spin valves, which are

structures that have a ‘free layer’ with magnetization normal to the plane and a ‘fixed layer’ with magnetization that is in-plane when the applied magnetic field is zero. However, once a

magnetic field is applied to allow a droplet to nucleate in the free layer, the fixed layer magnetization tilts out of plane. This tilting breaks symmetry and subjects the droplet to a drift

instability that changes its properties. Åkerman and colleagues have devised an approach that keeps symmetry unbroken, and thus allows imaging of droplets in their original states. The

approach involves changing the composition of the spin valve so that the fixed and free layers have strong perpendicular magnetic anisotropy and remain aligned. More specifically, the

composition of the fixed layer is multilayers of Co–Pd and the free layer is composed of Co–Ni multilayers. Åkerman and colleagues report the nucleation of the magnetic droplets by observing

changes in the electrical resistance of the droplets at sufficiently high magnetic field and current amplitudes. This is a preview of subscription content, access via your institution

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subscriptions * Read our FAQs * Contact customer support REFERENCES ORIGINAL ARTICLE * Chung, S. et al. Direct observation of Zhang–Li torque expansion of magnetic droplet solitons. _Phys.

Rev. Lett._ 120, 217204 (2018) Article  Google Scholar  Download references AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Associate Editor, Nature Reviews Physics

http://www.nature.com/natrevphys/ Zoe Budrikis Authors * Zoe Budrikis View author publications You can also search for this author inPubMed Google Scholar CORRESPONDING AUTHOR Correspondence

to Zoe Budrikis. RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Budrikis, Z. An unexpected twist. _Nat Rev Mater_ 3, 158 (2018).

https://doi.org/10.1038/s41578-018-0032-9 Download citation * Published: 28 June 2018 * Issue Date: July 2018 * DOI: https://doi.org/10.1038/s41578-018-0032-9 SHARE THIS ARTICLE Anyone you

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