Spin transfer torque switching for multi-bit per cell magnetic memory with perpendicular anisotropy

Sbiaa, R.; Law, Randall; Lua, S. Y. H.; Tan, Eng Leong; Tahmasebi, T.; Wang, C. C.; Piramanayagam, S. N.

doi:10.1063/1.3632075

Cited by 46 publications

(24 citation statements)

References 26 publications

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“…[8][9][10][11][12][13][14][15] In fact, materials with PMA have higher magnetic anisotropy energy compared to their counterparts with in-plane anisotropy. Thus, they are suitable for higher storage density without compromising their thermal stability.…”

Section: Introductionmentioning

confidence: 99%

Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers

Sbiaa

Al‐Omari

Kharel

et al. 2015

Journal of Applied Physics

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Sbiaa, R.; Al-Omari, I. A.; Kharel, Parashu R.; Ranjbar, M.; Sellmyer, David J.; Akerman, J.; and Piramanayagam, S. N., "Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers" (2015). Magnetization reversal of antiferromagnetically coupled (AFC) soft and hard (Co/Pd) multilayers was studied as a function of temperature. While the hard [Co(0.3 nm)/Pd(0.8 nm)] Â10 was kept unchanged, the softness of the [Co(t)/Pd(0.8 nm)] Â3 was controlled by varying the thickness t of the Co sublayer. Clear two-step hysteresis loops were observed for all the investigated multilayers with t ranging between 0.4 and 1 nm. The spin reorientation of the soft layer magnetization from in-plane direction to out-of-plane direction was investigated from 50 to 300 K. The antiferromagnetic field H AFC measured from the shift of the minor hysteresis loop reveals a good agreement to the quantum-well model. From the out-of-plane hysteresis loop of the uncoupled soft layer, its magnetization shows an in-plane orientation for t ! 0.6 nm. The strong H AFC helps to induce an out-of plane orientation of the soft layer with a linear decrease of its coercivity with temperature. These investigated structures show the possibility to reduce the unwanted stray field and improving the out-of-plane anisotropy even for relatively thicker soft layer. V C 2015 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 99%

Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers

Sbiaa

Al‐Omari

Kharel

et al. 2015

Journal of Applied Physics

Self Cite

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“…This result is not only useful for reducing the STT switching current but also to allow the switching only in a narrow range of frequency. This later finding is very useful for MTJs with two free layers as it was proposed for four bits per cell MRAM . In fact, by inserting two free layers with different anisotropy fields, it is possible to reverse their magnetizations at two different frequencies and avoiding thus the overwriting problem.…”

Section: Reduction Of Spin Torque Switching Currentmentioning

confidence: 77%

Recent Developments in Spin Transfer Torque MRAM

Sbiaa

Piramanayagam

2017

Physica Rapid Research Ltrs

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Spin transfer torque (STT) switching-based magnetic random access memory (MRAM) is gaining significant industrial and academic attention due to its potential application as a non-volatile memory device in computing devices, smartphones, and so on. STT-MRAM devices with in-plane magnetization configuration have been marketed as niche products. Devices with out-ofplane magnetization are being considered for embedded memory as the first step. Aggressive goals include replacing dynamic random access memory (DRAM) with STT-MRAM. This review article introduces the basics of STT-MRAM and describes the recent progress in overcoming certain challenges such as reduction of power consumption and increase of storage density, which will make it a strong competitor for DRAM. Reduction of Spin Torque Switching CurrentThe main advantage of STT-MRAM compared to magnetic fieldbased MRAM is its scalability. For a given anisotropy energy K u , the

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“…[11] gives a schematic overview of topical subjects in the rapidly evolving fields of spintronics and magnetoelectronics [8,11]. Besides the familiar control of magnetic devices by external magnetic fields, new and exciting phenomena have been discovered recently, including control by a spin polarized current [133], by electric fields [134][135][136][137] or by photonic fields in ultrafast light pulses [11]. Most of these phenomena are observed in nanoscale magnetic systems.…”

Section: Discussionmentioning

confidence: 99%

Application of Mössbauer spectroscopy in magnetism

Keune

2012

Hyperfine Interact

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An overview is provided on our recent work that applies 57 Fe Mössbauer spectroscopy to specific problems in nanomagnetism. 57 Fe conversion electron Möss-bauer spectroscopy (CEMS) in conjunction with the 57 Fe probe layer technique as well as 57 Fe nuclear resonant scattering (NRS) were employed for the study of various nanoscale layered systems: (i) metastable fct-Fe; a strongly enhanced hyperfine magnetic field B hf of ∼39 T at 25 K was observed in ultrahigh vacuum (UHV) on uncoated three-monolayers thick epitaxial face-centered tetragonal (fct) 57 Fe(110) ultrathin films grown by molecular-beam epitaxy (MBE) on vicinal Pd(110) substrates; this indicates the presence of enhanced Fe local moments, μ Fe , as predicted theoretically; (ii) Fe spin structure; by applying magnetic fields, the Fe spin structure during magnetization reversal in layered (Sm-Co)/Fe exchange spring magnets and in exchange-biased Fe/MnF 2 bilayers was proven to be non-collinear and depth-dependent; (iii) ferromagnet/semiconductor interfaces for electrical spin injection; CEMS was used as a diagnostic tool for the investigation of magnetism at the buried interface of Fe electrical contacts on the clean surface of GaAs(001) and GaAs(001)-based spin light-emitting diodes (spin LED) with in-plane or out-ofplane Fe spin orientation; the measured rather large average hyperfine field of ∼27 T at 295 K and the distribution of hyperfine magnetic fields, P(B hf ), provide evidence for the absence of magnetically "dead" layers and the existence of relatively large Fe moments (μ Fe ∼ 1.8 μ B ) at the ferromagnet/semiconductor interface. -Finally, a short outlook is given for potential applications of Mössbauer spectroscopy on topical subjects of nanomagnetism/spintronics.

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Spin transfer torque switching for multi-bit per cell magnetic memory with perpendicular anisotropy

Cited by 46 publications

References 26 publications

Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers

Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers

Recent Developments in Spin Transfer Torque MRAM

Application of Mössbauer spectroscopy in magnetism

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