New innovations, applications and computing advancements are coming at a blistering pace and memory is at the heart of all of them. To date, different types of electric control methods have been developed. Worledge spin transfer torque magnetoresistive randomaccess memory sttmram is an emerging nonvolatile memory that uses magnetic tunnel junctions mtjs to store information. Our intention is to be accessible to beginning graduate students. Chifeng pai, from spin transfer torque, spin hall torque, to spinorbit torque part ii. Spin transfer torque magnetoresistive randomaccess memory sttmram is an emerging nonvolatile memory that uses magnetic tunnel junctions mtjs to store information. 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. The memory unit includes a magnetic tunnel junction data cell electrically coupled to a bit line and a source line. 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.
In an sttmram device, the spin of the electrons is flipped using a spin polarized current. Stiles national institute of standards and technology, gaithersburg, md 208998412 a. Pdf introduction to spin transfer torque researchgate. The flow of spins is determined by the spin dependent transport properties, like conductivity, interface resistance, and spin flip scattering in the magnetic multilayer. Spin transfer torque devices market 20202025 report offers a comprehensive valuation of the marketplace. 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. Spin transfer torque with spin diffusion in magnetic tunnel junctions, phys. A twoterminal perpendicular spintransfer torque pstt based neuron with a 100. Spin transfer torque preliminary theory free electrons particle transport distribution of electron states spin. Remarkable progress in stt switching with mgo mtjs and increasing interest in sttmram in semiconductor industry have been witnessed in recent years. Mechanism and assessment of spin transfer torque stt based memory by iong ying loh b. Spintransfer torque stt is an effect in which the orientation of a magnetic layer in a magnetic. Spintransfer torque in magnetic nanostructures smartech. 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.
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. 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. Spin transfer torque corresponds to the interaction of a spin polarized electronic current with the local magnetization. Applied physics 2007 university of malaya submitted to. The report examines factors influencing growth of the market along with detailing of the key trends, drivers, restraints, regional trends, and opportunities.
A transmission gatebased spin transfer torque memory unit is described. Interaction of a spin polarized current with a magnetic layer. Spin transfer torque on magnetic insulators to cite this article. This tutorial article introduces the physics of spin transfer torques in magnetic devices. Slonczewski model, zhangli model, spin hall effect. Us7974119b2 transmission gatebased spintransfer torque. Graphene is an ideal channel material in this context due to its long spin diffusion length, gatetunable. Materials for spintransfertorque magnetoresistive random. It performed well in the integrateandfire event of the input voltage pulse spike cycles, which.
To explain, in contrast to electronic devices that. Characterization of spin transfer torque and magnetization manipulation in magnetic nanostructures chen wang, ph. Pdf spin transfer torque corresponds to the interaction of a spin polarized electronic current with the local magnetization. Spin transfer torque can be used to flip the active elements in magnetic randomaccess memory. 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. 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. Spin transfer torquethe transfer of angular momentum from a spinpolarized current to a ferromagnets magnetizationhas already found commercial application in memory devices, but 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 in magnetic structures occurs when the transverse component of the spin current that flows from the nonmagnetic medium to ferromagnetic. Spin transfer torques ralph group cornell university. 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. Magnetic moment is transferred from the conduction electrons to the. Pdf spintransfer torque and dynamics jacques miltat.
It has been demonstrated that due to their extreme scal. Achieving quantitative measurements of the spintransfertorque vector in magnetic tunnel junctions. Mechanism and assessment of spin transfer torque stt based. Cornell university 2012 this dissertation describes a number of research projects with the common. In partial fulfillment of the requirements for the. Spintransfer and spinorbit torques, current topics. 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.
This phenomenon, known as the spin transfer torque st t, has mainly been studied on a larger scale. Introduction to spin torques and spinorbit torques in metal. The term spintronics is a portmanteau of spin transportelectronics. A comparative study between spintransfertorque stt and spinhalleffect she switching mechanisms in pmtj using spice ibrahim ahmed, zhengyang zhao, meghna g. Slonczewski predicted that the spin transfer torque from a direct current could excite two qualitatively different types of magnetic behaviors.
Al, hyperscale datacenters, selfdriving cars, iot, mobile and more. A twoterminal perpendicular spintransfer torque based. 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. Spintransfer torques cpp, cip and spinorbit torques. Xingtao jia et al 2011 epl 96 17005 view the article online for updates and enhancements. 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. Magnetization switching by combining electric field and spintransfer. Spin transfer torque in the semiconductorferromagnetic. Pdf study of spin transfer torque stt and spin orbit torque. This effect is achieved in a magnetic tunnel junction mtj or a spin valve, and sttmram devices use stt tunnel junctions sttmtj. 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.
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. 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 torqueram devices as a future nonvolatile. Onchip caches built on multilevel spintransfer torque ram. Pdf we present a theoretical study of the spintransfer torque vector and the tunneling magnetoresistance tmr for symmetric magnetic tunnel junctions. Dec 19, 2016 chifeng pai, from spin transfer torque, spin hall torque, to spin orbit torque part ii. A spin polarized current is created by passing a current though a thin magnetic layer. Index termsferromagnetic resonance, spintransfer torque stt, stt magnetoresistive random access memory mram. Key concepts in spin transport in fmnm systems interaction of a spin polarized current with a magnetic layer spin transfer torque stt.
Pdf spintransfer torque in magnetic tunnel junctions. Grandis press release describing partnership with hynix pdf. In this article, we investigate the use of multilevel spin transfer torque ram sttram cells in the design of processor caches. Our intention is that it be accessible to beginning graduate students. Spintransfer torque generated by a topological insulator. Mechanism and assessment of spin transfer torque stt. A comparative study between spintransfertorque stt and. Spin transfer torque in a graphene lateral spin valve. Kim abstractspin transfer torque magnetoresistive random access memory sttmram is the leading candidate for spin. Zangwill school of physics, georgia institute of technology, atlanta, ga 303320430. Efficient electrical control of magnetism is a major goal of spin based electronics. Spintransfer torque magnetic tunneling junction devices capable of a multilevel threedimensional 3d information processing are studied in the sub20nm size range. 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 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.
Spin transfer torque induced switching in magnetic tunnel. Oct 15, 20 spinbased devices are widely discussed for postcomplementary metaloxidesemiconductor cmos applications. In this slow thermal activated switching regime, the switching current is dependent on the current pulse width. Emerging applications, especially those using batteries, such as arvr, iot and many machine learning. One is based on the spintransfer torque stt effect induced by. In many setups, spin polarized current is used to switch the magnetization of a magnetic layer. Pdf spin transfer torque celestine preetham lawrence. Measurement of the spintransfertorque vector in magnetic. Magnetic systems are promising candidates for next generation memory due to their intrinsic nonvolatility and low dissipation during switching 1. A multiscale picture a powerful driving force behind the development of fast, high density, nonvolatile memory technology. Experimental observation of the optical spin transfer torque.1373 697 1091 447 1299 399 482 185 912 33 486 1147 385 372 204 696 974 353 991 670 1294 1358 273 1224 1542 1307 287 1156 1180 743 179 769 1315 333 295 574