Final Report Summary - SPORT FOR MEMORY (Spin-Orbit Torques for magnetic memory applications)
Current research in spintronics focuses on a new type of memory device where the information is stored in the resistance state of Magnetic Tunnel Junctions (MTJ). This device generates high expectations, since it combines most qualities (fast, dense, cheap...) encountered separately in existing random access memories, among which one of the key features is the non-volatility.
This proposal is about using a novel phenomenon of current induced magnetization switching based on spin orbit torques (SOT). This new approach is scalable, non-destructive to the barrier and unlike any other switching mechanism, it allows to simultaneously improve the thermal stability and switching efficiency.
In this context, our activity is twofold: i) we improve the understanding of the basic phenomena required to control the magnetization by SOT ii) we fabricate proof of concept devices to stimulate the interest of microelectronic companies for this new type of device.
Regarding the fundamental aspect of our research, in the first part of the project, we have designed a tool for the complete measurement of the anatomy of the spin-orbit torques (SOT). In the second period of the project this method was extended for materials with in-plane magnetization. We characterized a wide variety of in-plane and out-of-plane materials to understand the nature of the SOT. We are now able to answer important question regarding the underlying mechanism. For example we have separated the contributions arising from the ferromagnetic/heavy-metal (FM/HM) interface and from the HM bulk contributions; we also quantified the SOT created at the oxide/ferromagnet interface.
Concerning the applicative part we have fabricate a three terminal device consisting of a perpendicularly magnetized magnetic tunnel junction placed on a Ta electrode. We have achieved both reading (TMR=50%) and sub-ns writing by SOT on the same device.
Furthermore, we have developed a new method for SOT switching which no longer requires the use of an in-plane bias field for bipolar magnetization reversal. This is a major breakthrough, since the use of the in-plane field was the most important fundamental drawback of SOT-MRAM.
This proposal is about using a novel phenomenon of current induced magnetization switching based on spin orbit torques (SOT). This new approach is scalable, non-destructive to the barrier and unlike any other switching mechanism, it allows to simultaneously improve the thermal stability and switching efficiency.
In this context, our activity is twofold: i) we improve the understanding of the basic phenomena required to control the magnetization by SOT ii) we fabricate proof of concept devices to stimulate the interest of microelectronic companies for this new type of device.
Regarding the fundamental aspect of our research, in the first part of the project, we have designed a tool for the complete measurement of the anatomy of the spin-orbit torques (SOT). In the second period of the project this method was extended for materials with in-plane magnetization. We characterized a wide variety of in-plane and out-of-plane materials to understand the nature of the SOT. We are now able to answer important question regarding the underlying mechanism. For example we have separated the contributions arising from the ferromagnetic/heavy-metal (FM/HM) interface and from the HM bulk contributions; we also quantified the SOT created at the oxide/ferromagnet interface.
Concerning the applicative part we have fabricate a three terminal device consisting of a perpendicularly magnetized magnetic tunnel junction placed on a Ta electrode. We have achieved both reading (TMR=50%) and sub-ns writing by SOT on the same device.
Furthermore, we have developed a new method for SOT switching which no longer requires the use of an in-plane bias field for bipolar magnetization reversal. This is a major breakthrough, since the use of the in-plane field was the most important fundamental drawback of SOT-MRAM.