Mechanism and assessment of spin transfer torque stt based. A spin polarized current is created by passing a current though a thin magnetic layer. Pdf spin transfer torque celestine preetham lawrence. Slonczewski predicted that the spin transfer torque from a direct current could excite two qualitatively different types of magnetic behaviors. Spintransfer torque devices market to rise while making huge. Oct 15, 20 spinbased devices are widely discussed for postcomplementary metaloxidesemiconductor cmos applications. This tutorial article introduces the physics of spin transfer torques in magnetic devices. Materials for spin transfer torque magnetoresistive randomaccess memory shinji yuasa kazuhiro hono guohan huand daniel c. Pdf introduction to spin transfer torque researchgate.
The term spintronics is a portmanteau of spin transportelectronics. Key concepts in spin transport in fmnm systems interaction of a spin polarized current with a magnetic layer spin transfer torque stt. Forces inside system third law force pairs torque int sum 0 the only torques that can change the angular momentum of a system are the external torques acting on a system. In partial fulfillment of the requirements for the. Magnetic systems are promising candidates for next generation memory due to their intrinsic nonvolatility and low dissipation during switching 1. Grandis press release describing partnership with hynix pdf. Spin transfer torque can be used to flip the active elements in magnetic randomaccess memory.
Spin transfer torque magnetic randomaccess memory sttram or sttmram is a nonvolatile memory with nearzero leakage power consumption which is a major advantage over chargebased memories such as sram and dram. Spin transfer torque magnetoresistive randomaccess memory sttmram is an emerging nonvolatile memory that uses magnetic tunnel junctions mtjs to store information. Dec 19, 2016 chifeng pai, from spin transfer torque, spin hall torque, to spin orbit torque part ii. Pdf spintransfer torque and dynamics jacques miltat. It has been predicted that a processors caches could occupy as much as 90% of chip area a few technology nodes from the current ones. This effect is achieved in a magnetic tunnel junction mtj or a spin valve, and sttmram devices use stt tunnel junctions sttmtj. Magnetic moment is transferred from the conduction electrons to the. Jul 23, 2014 charge flowing in a thin film of the topological insulator bismuth selenide at room temperature can lead to spin accumulation in the insulator and a resultant strong spin transfer torque on an. Spin transfer torque corresponds to the interaction of a spin polarized electronic current with the local magnetization. Spin transfer torque stt induced magnetization switching and oscillation in nanometer scale magnetoresistance mr devices have been studied intensively due to its direct application in the nonvolatile stt random access memory sttram and its potential application in the high frequency spin torque oscillatior sto. To explain, in contrast to electronic devices that. A multiscale picture a powerful driving force behind the development of fast, high density, nonvolatile memory technology.
Spin transfer torqueram devices as a future nonvolatile. Mtjs with a crystalline mgo001 tunnel barrier sandwiched between ferromagnetic layers, such as cofeb, exhibit giant tunnel magnetoresistance, which is used to readout the stt. Mechanism and assessment of spin transfer torque stt. Xingtao jia et al 2011 epl 96 17005 view the article online for updates and enhancements. Kim abstractspin transfer torque magnetoresistive random access memory sttmram is the leading candidate for spin. Introduction to spin torques and spinorbit torques in metal. Cornell university 2012 this dissertation describes a number of research projects with the common. A twoterminal perpendicular spintransfer torque pstt based neuron with a 100. Spin transfer torque on magnetic insulators to cite this article. Spin transfer torque with spin diffusion in magnetic tunnel junctions, phys. Interaction of a spin polarized current with a magnetic layer. Zangwill school of physics, georgia institute of technology, atlanta, ga 303320430. In an sttmram device, the spin of the electrons is flipped using a spin polarized current. Spin transfer technologies new psc structure shows a lot of promise to solve a number of those issues and pave the path for mram to take a significant share of the embedded memory market.
In this article, we investigate the use of multilevel spin transfer torque ram sttram cells in the design of processor caches. Us7974119b2 transmission gatebased spintransfer torque. The memory unit includes a magnetic tunnel junction data cell electrically coupled to a bit line and a source line. Slonczewski model, zhangli model, spin hall effect. Pdf spintransfer torque in magnetic tunnel junctions. Spintransfer torque in magnetic nanostructures smartech. Applied physics 2007 university of malaya submitted to. The net external torque acting on a system of particles is equal to the time rate of change of the systems total angular momentum l. Worledge spin transfer torque magnetoresistive randomaccess memory sttmram is an emerging nonvolatile memory that uses magnetic tunnel junctions mtjs to store information. Spin transfer torquethe transfer of angular momentum from a spinpolarized current to a ferromagnets magnetizationhas already found commercial application in memory devices, but the. Spintransfer torque stt is an effect in which the orientation of a magnetic layer in a magnetic.
Experimental observation of the optical spin transfer torque. A comparative study between spintransfertorque stt and. In many setups, spin polarized current is used to switch the magnetization of a magnetic layer. Ad and fl components stt on domain walls spin pumping sttinduced magnetization dynamics spin orbit coupling and spin orbit torques sot spin hall and rashba effects sot measurements. Challenges and prospects at a finite temperature, thermal agitation plays an important role in reducing the switching current at long current pulses 10 ns. Spin transfer torques ralph group cornell university. A comparative study between spintransfertorque stt and spinhalleffect she switching mechanisms in pmtj using spice ibrahim ahmed, zhengyang zhao, meghna g. Spin transfer torque in the semiconductorferromagnetic.
In this slow thermal activated switching regime, the switching current is dependent on the current pulse width. Pdf study of spin transfer torque stt and spin orbit torque. Spin transfer torque induced switching in magnetic tunnel. Spin transfer torque devices market 20202025 report offers a comprehensive valuation of the marketplace. Spintransfer torques occur in magnetic heterostructures because the transverse component of a spin current that flows from a nonmagnet into a ferromagnet is absorbed at the interface.
Efficient electrical control of magnetism is a major goal of spin based electronics. Magnetization switching by combining electric field and spintransfer. Materials for spintransfertorque magnetoresistive random. Spintransfer torque generated by a topological insulator.
Spin transfer torques occur in magnetic heterostructures because the transverse component of a spin current that flows from a nonmagnet into a ferromagnet is absorbed at the interface. A number of spin device ideas propose using spin current to carry information coherently through a spin channel and transfering it to an output magnet by spin transfer torque. Spintransfer and spinorbit torques, current topics. Chifeng pai, from spin transfer torque, spin hall torque, to spinorbit torque part ii. This phenomenon, known as the spin transfer torque st t, has mainly been studied on a larger scale. Characterization of spin transfer torque and magnetization manipulation in magnetic nanostructures chen wang, ph. Spintransfer torques cpp, cip and spinorbit torques. Spin transfer torque in a graphene lateral spin valve. Pdf spin transfer torque corresponds to the interaction of a spin polarized electronic current with the local magnetization. Spin transfer torque preliminary theory free electrons particle transport distribution of electron states spin. New innovations, applications and computing advancements are coming at a blistering pace and memory is at the heart of all of them. Achieving quantitative measurements of the spintransfertorque vector in magnetic tunnel junctions. Spin transfer torque stt switching demonstrated in submicron sized magnetic tunnel junctions mtjs has stimulated considerable interest for developments of stt switched magnetic random access memory sttmram. To date, different types of electric control methods have been developed.
Mechanism and assessment of spin transfer torque stt based memory by iong ying loh b. Charge flowing in a thin film of the topological insulator bismuth selenide at room temperature can lead to spin accumulation in the insulator and a. Index termsferromagnetic resonance, spintransfer torque stt, stt magnetoresistive random access memory mram. The report examines factors influencing growth of the market along with detailing of the key trends, drivers, restraints, regional trends, and opportunities. Emerging applications, especially those using batteries, such as arvr, iot and many machine learning.
Our intention is to be accessible to beginning graduate students. Al, hyperscale datacenters, selfdriving cars, iot, mobile and more. Measurement of the spintransfertorque vector in magnetic. One is based on the spintransfer torque stt effect induced by. Remarkable progress in stt switching with mgo mtjs and increasing interest in sttmram in semiconductor industry have been witnessed in recent years. Spin transfer torque in magnetic structures occurs when the transverse component of the spin current that flows from the nonmagnetic medium to ferromagnetic. Onchip caches built on multilevel spintransfer torque ram. Spintransfer torque magnetic tunneling junction devices capable of a multilevel threedimensional 3d information processing are studied in the sub20nm size range. This is the introductory paper for a cluster of \current perspectives articles on spin transfer torques published in volume 320 of the journal of magnetism and magnetic. It performed well in the integrateandfire event of the input voltage pulse spike cycles, which. A transmission gatebased spin transfer torque memory unit is described. Stiles national institute of standards and technology, gaithersburg, md 208998412 a. Graphene is an ideal channel material in this context due to its long spin diffusion length, gatetunable.
The flow of spins is determined by the spin dependent transport properties, like conductivity, interface resistance, and spin flip scattering in the magnetic multilayer. This thesis describes experimental studies of the spin transfer torque induced switching in magnetic tunnel junctions mtj for the application of spin transfer torque random access memory sttram. Applied physics 2007 university of malaya submitted to the department of materials science and engineering. Pdf we present a theoretical study of the spintransfer torque vector and the tunneling magnetoresistance tmr for symmetric magnetic tunnel junctions. When an electron spin carried by the current interacts with a magnetic layer, the exchange interaction leads to torques between the spin and the magnetization. Our intention is that it be accessible to beginning graduate students. It has been demonstrated that due to their extreme scal.
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