Abstract
Spin based logic devices have attracted a lot of research interest due to their potential low-power operation, non-volatility and possibility to enable new computing applications. Here we present an experimental demonstration of a novel spin logic device working at room temperature without the requirement of an external magnetic field. Our device is based on a pair of coupled in-plane magnetic anisotropy (IMA) magnet and a perpendicular magnetic anisotropy (PMA) magnet. The information written in the state of the IMA magnet is transferred to the state of the PMA magnet by means of a symmetry breaking dipolar field, while the two layers are electrically isolated. In addition to having the basic tenets of a logic device, our device has inbuilt memory, taking advantage of the non-volatility of nanomagnets. In another mode of operation, the same device is shown to have the functionality of a true random number generator (TRNG). The combination of logic functionality, nonvolatility and capability to generate true random numbers all in the same spin logic device, makes it uniquely suitable as a hardware for many new computing ideas.
Highlights
Building logic units with spintronic elements is a topic of great interest as they can offer the functionality of a logic device at lower power and at the same time serve as memory elements, owing to the non-volatile nature of nanomagnets
We begin with depositing a composite stack of perpendicular magnetic anisotropy (PMA) and in-plane magnetic anisotropy (IMA) magnet separated by 6–7 nm MgO that serves as the electrical isolation between them
The Ta layer is patterned into a Hall bar with the composite IMA-PMA stack sitting on top shaped into an ellipse with major and minor diameter of 3 μm and 1 μm, respectively (Fig. 2(d))
Summary
Building logic units with spintronic elements is a topic of great interest as they can offer the functionality of a logic device at lower power and at the same time serve as memory elements, owing to the non-volatile nature of nanomagnets. In contrast to the originally proposed implementation of CSL (Fig. 1(a) left), the coupling between WRITE and READ is realized by a very small dipolar field from the IMA that is sufficient to break the symmetry of GSHE switching of the PMA (Fig. 1(a) right) This weak coupling relaxes the design constraints on the isolation layers www.nature.com/scientificreports/. We demonstrate that the same device is capable of producing true random binary digits through the stochastic switching of its PMA, when the read current through the GSHE layer is above a certain value We show that this functionality is only possible if the amount of dipolar field exerted by the IMA on the PMA is engineered properly
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