Magnetization switching in ferromagnets by adsorbed chiral molecules without current or external magnetic field

• Published in: Nature communications Vol. 8; no. 1; p. 14567
• Main Authors: Ben Dor, Oren, Yochelis, Shira, Radko, Anna, Vankayala, Kiran, Capua, Eyal, Capua, Amir, Yang, See-Hun, Baczewski, Lech Tomasz, Parkin, Stuart Stephen Papworth, Naaman, Ron, Paltiel, Yossi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23-02-2017; Nature Publishing Group; Nature Portfolio
• Subjects: 140/146; 142/126; 639/766/119/1001; 639/766/119/544; 639/766/119/997; 639/925/927/998; Adsorption; Electrons; Handedness; Humanities and Social Sciences; Microscopy; multidisciplinary; Physics; Random access memory; Science; Science (multidisciplinary); Topography; Israel
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms14567

Ferromagnets are commonly magnetized by either external magnetic fields or spin polarized currents. The manipulation of magnetization by spin-current occurs through the spin-transfer-torque effect, which is applied, for example, in modern magnetoresistive random access memory. However, the current density required for the spin-transfer torque is of the order of 1 × 10
6
 A·cm
−2
, or about 1 × 10
25
electrons s
−1
cm
−2
. This relatively high current density significantly affects the devices’ structure and performance. Here we demonstrate magnetization switching of ferromagnetic thin layers that is induced solely by adsorption of chiral molecules. In this case, about 10
13
electrons per cm
2
are sufficient to induce magnetization reversal. The direction of the magnetization depends on the handedness of the adsorbed chiral molecules. Local magnetization switching is achieved by adsorbing a chiral self-assembled molecular monolayer on a gold-coated ferromagnetic layer with perpendicular magnetic anisotropy. These results present a simple low-power magnetization mechanism when operating at ambient conditions.
Spin manipulation in memory devices typically requires large electrical currents, limiting performance. Here the authors demonstrate magnetization switching in ferromagnetic films by depositing chiral molecules, making use of a proximity effect without needing magnetic or electric fields.