Ultrafast switching in a synthetic antiferromagnetic magnetic random-access memory device

Bergman, Anders; Skubic, Björn; Hellsvik, Johan; Nordström, Lars; Delin, Anna; Eriksson, Olle

doi:10.1103/physrevb.83.224429

Cited by 35 publications

(20 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…12–17 In these examples, the important physics is the tuning of stray fields to manipulate stability and sensitivity, and the extra degrees of freedom provided by the layers and coupling between them. The latter leads to additional – with respect to a single magnetic layer – dynamical modes that alter the dynamics and may decrease the switching time of the memory cells.…”

Section: Statics and Dynamicsmentioning

confidence: 99%

Synthetic antiferromagnetic spintronics

et al. 2018

View full text Add to dashboard Cite

Spintronic and nanomagnetic devices often derive their functionality from layers of different materials and the interfaces between them. This is especially true for synthetic antiferromagnets — two or more ferromagnetic layers that are separated by metallic spacers or tunnel barriers and which have antiparallel magnetizations. Here, we discuss the new opportunities that arise from synthetic antiferromagnets, as compared to crystal antiferromagnets or ferromagnets.

show abstract

Section: Statics and Dynamicsmentioning

confidence: 99%

Synthetic antiferromagnetic spintronics

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Several mechanisms for shorter switching speeds have been proposed, e.g., toggle switching [7], all-optical switching [8], switching accelerated by antiferromagnetic exchange [9], and so forth. One recent suggestion is the socalled inertia-driven switching [10].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Analysis of Inertia-like Switching in Magnets: Applications to a Synthetic Antiferromagnet

et al. 2012

Self Cite

View full text Add to dashboard Cite

The magnetization dynamics of a synthetic antiferromagnet subjected to a short-magnetic-field pulse has been studied by using a combination of first principles calculations and atomistic spin-dynamics simulations. We observe switching phenomena on the time scale of tens of picoseconds, and inertia-like behavior in the magnetization dynamics. We explain the latter in terms of a dynamic redistribution of magnetic energy from the applied-field pulse to other possible energy terms, such as the exchange interaction and the magnetic anisotropy, without invoking concepts such as the inertia of an antiferromagnetic vector. We also demonstrate that such dynamics can also be observed in a ferromagnetic material where the incident-field pulse pumps energy to the magnetic anisotropy.

show abstract

“…[34][35][36][37][38][39][40] SyF based spintronic devices have the advantage of higher thermal stability, smaller stray magnetic fields, faster switching speed, and reduced threshold switching current as compared to single ferromagnetic free layers. [34][35][36][37][38][39][40] Klein et al 40 predicted that an antiferromagnetically coupled SyF layer with uncompensated magnetization can generate microwave oscillations at zero applied magnetic field.Here we predict that a ferromagnetically coupled SyF can also be driven into dynamical precessional states, which, however, are surrounded in parameter space by static canted states with noncollinear magnetizations. We use an analytical approach to determine the stability regimes of the SyF system and confirm results by numerical simulations.…”

mentioning

confidence: 99%

“…[29][30][31][32][33] Recently, synthetic ferromagnets (SyFs) composed of two ferromagnetic layers separated by a very thin nonmagnetic spacer have been used to replace the free layer of a spin valve or MTJ. [34][35][36][37][38][39][40] SyF based spintronic devices have the advantage of higher thermal stability, smaller stray magnetic fields, faster switching speed, and reduced threshold switching current as compared to single ferromagnetic free layers. [34][35][36][37][38][39][40] Klein et al 40 predicted that an antiferromagnetically coupled SyF layer with uncompensated magnetization can generate microwave oscillations at zero applied magnetic field.…”

mentioning

confidence: 99%

Field-free synthetic-ferromagnet spin torque oscillator

et al. 2013

View full text Add to dashboard Cite

We study the magnetization dynamics of spin valve structures with a free composite synthetic ferromagnet (SyF) that consists of two ferromagnetic layers coupled through a normal metal spacer. A ferromagnetically coupled SyF can be excited into dynamical precessional states by an applied current without external magnetic fields. We analytically determine the stability of these states in the space spanned by the current density and SyF interlayer exchange coupling. Numerical simulations confirm our analytical results. The transfer of angular momentum between the magnetic layers of current-driven spin valves (spin-transfer torque) has not been so long ago predicted 1,2 and experimentally confirmed.3,4 The implied efficient electrical control of magnetizations motivated the pursuit of new research directions. When the current density exceeds a critical value, the spintransfer torque can switch the magnetization to a different static configuration without the necessity of applied magnetic fields, which makes it attractive for next generation magnetoresistive random access memory (MRAM) application. 3,[5][6][7] Under an external magnetic field, the spin-transfer torque can also drive the magnetization into sustainable coherent oscillations spanning a wide frequency range from a few MHz to several hundred GHz.3,5-11 High frequency magnetic oscillations generate a coherent microwave voltage signal through the giant magnetoresistance (GMR) in metallic spin valves or through the tunneling magnetoresistance (TMR) in magnetic tunnel junctions (MTJs). This effect can be used in so-called spin-torque oscillators (STO), which has many advantages including wide tunability, 12 very high modulation rates, 13,14 compact device size, and high compatibility with standard CMOS processes. 15,16 Thus STO is appealing for high frequency microwave applications including microwave emitters, modulators, and detectors.17 However, the necessity of an applied magnetic field up to ∼1 T has severely limited the potential of these STOs for microwave generation and wireless communication applications. Recently, various solutions have been proposed to enable zero-field operation, viz., STO with a perpendicularly magnetized fixed 18 or spin valves with out-of-plane magnetized free layer, 19,20 magnetic vortex oscillators, 21-27 wavy-torque STO by judicially choosing free and fixed layer materials with different spin diffusion lengths, 28 and a tilted magnetization of the fixed layer with respect to the film plane. [29][30][31][32][33] Recently, synthetic ferromagnets (SyFs) composed of two ferromagnetic layers separated by a very thin nonmagnetic spacer have been used to replace the free layer of a spin valve or MTJ. [34][35][36][37][38][39][40] SyF based spintronic devices have the advantage of higher thermal stability, smaller stray magnetic fields, faster switching speed, and reduced threshold switching current as compared to single ferromagnetic free layers. [34][35][36][37][38][39][40] Klein et al. 40 predicted that an antiferromagnetically co...

show abstract

Ultrafast switching in a synthetic antiferromagnetic magnetic random-access memory device

Cited by 35 publications

References 27 publications

Synthetic antiferromagnetic spintronics

Synthetic antiferromagnetic spintronics

Theoretical Analysis of Inertia-like Switching in Magnets: Applications to a Synthetic Antiferromagnet

Field-free synthetic-ferromagnet spin torque oscillator

Contact Info

Product

Resources

About