Perpendicular magnetic tunnel junction (p-MTJ) spin-valves designed with a top Co2Fe6B2 free layer and a nanoscale-thick tungsten bridging and capping layer

Lee, Seung‐Eun; Shim, Tae‐Hun; Park, Jea‐Gun

doi:10.1038/am.2016.162

Cited by 22 publications

(15 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To address those concerns, W was recently reported to replace Ta as spacer and bridging layers in top-pinned p-MTJ films. [32][33][34][35][36][37] A TMR of 141% after 400 °C annealing 2 and a Δ of 61 have been obtained from blank films. 34 These improvements were partially attributed to the suppression of atom diffusion and crystalline structure of the W layer, whereas the essential role of W layers in TMR enhancement has not been clearly revealed.…”

mentioning

confidence: 99%

Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistance

et al. 2018

View full text Add to dashboard Cite

Perpendicular magnetic tunnel junctions based on MgO/CoFeB structures are of particular interest for magnetic random-access memories because of their excellent thermal stability, scaling potential, and power dissipation. However, the major challenge of current-induced switching in the nanopillars with both a large tunnel magnetoresistance ratio and a low junction resistance is still to be met. Here, we report spin transfer torque switching in nano-scale perpendicular magnetic tunnel junctions with a magnetoresistance ratio up to 249% and a resistance area product as low as 7.0 Ω µm2, which consists of atom-thick W layers and double MgO/CoFeB interfaces. The efficient resonant tunnelling transmission induced by the atom-thick W layers could contribute to the larger magnetoresistance ratio than conventional structures with Ta layers, in addition to the robustness of W layers against high-temperature diffusion during annealing. The critical switching current density could be lower than 3.0 MA cm−2 for devices with a 45-nm radius.

show abstract

mentioning

confidence: 99%

Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistance

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Lee et al performed controlled experiments in two p‐MTJs with W and Ta heavy metal layers . Two stacks were ex situ annealed at the back‐end‐of‐line temperature of 400 °C, as shown in Figure .…”

Section: Modulation Of Hm/fm Interface For High Tmrmentioning

confidence: 99%

Section: Modulation Of Hm/fm Interface For High Tmrmentioning

confidence: 99%

“…Further experiments demonstrate that, apart from the CoFeB/MgO interface, the heavy metal (HM) layer adjacent to the FM layer is also very important for device performances, as shown in Figure . For instance, by replacing the widely used HM material tantalum (Ta) with tungsten (W), both the interfacial PMA and the TMR ratio in the HM/CoFeB/MgO structure can be increased . Moreover, the performance of the Ta/CoFeB/MgO structure deteriorates rapidly when the annealing temperature ( T a ) exceeds 300 °C, while that of the W/CoFeB/MgO structure remains stable at annealing temperature up to 450 °C.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modulation of Heavy Metal/Ferromagnetic Metal Interface for High‐Performance Spintronic Devices

Peng

Zhu

Zhou

et al. 2019

Adv Elect Materials

View full text Add to dashboard Cite

Spintronic devices such as magnetic tunnel junctions and skyrmions have attracted considerable attention due to features such as nonvolatility, high scalability, low power, and high speed. Over the past few years, innovative materials and new structures in this field have resulted in the emergence of new phenomena and exciting device performance. It has been found that the heavy metal (HM)/ferromagnetic metal (FM) interface plays an essential role in spintronic devices. Spintronic device performance can be significantly enhanced through proper modulation of this interface. Recent progress in this blooming field is reviewed with specific emphasis on the HM/FM interface. Investigations into HM/FM-interface-related phenomena, including perpendicular magnetic anisotropy, tunnel magnetoresistance, magnetic damping, spin-orbit torque, and Dzyaloshinskii-Moriya interaction, are put into context. Guidelines for realizing high-performance spintronic devices are provided, and an outlook on their future research direction and potential applications is given.

show abstract

“…[21][22][23] Recently, experiments have investigated the influence on TMR caused by capping layers, and drawn the conclusion that a higher TMR can be achieved in MTJs with W capping layers instead of Ta. [24][25][26] However, the understanding of the essential influence on TMR caused by capping layers remains unclear, leading to difficulties in TMR optimization for MTJ nano-pillars.…”

mentioning

confidence: 99%

Large influence of capping layers on tunnel magnetoresistance in magnetic tunnel junctions

Zhou

Zhao

Wang

et al. 2016

Applied Physics Letters

View full text Add to dashboard Cite

It has been reported in experiments that capping layers which enhance the perpendicular magnetic anisotropy (PMA) of magnetic tunnel junctions (MTJs) induce great impact on the tunnel magnetoresistance (TMR). To explore the essential influence caused by capping layers, we carry out ab initio calculations on TMR in the X(001)|CoFe(001)|MgO(001)|CoFe(001)|X(001) MTJ, where X represents the capping layer material which can be tungsten, tantalum or hafnium. We report TMR in different MTJs and demonstrate that tungsten is an ideal candidate for a giant TMR ratio. The transmission spectrum in Brillouin zone is presented. It can be seen that in the parallel condition of MTJ, sharp transmission peaks appear in the minority-spin channel. This phenomenon is attributed to the resonant tunnel transmission effect and we explained it by the layer-resolved density of states (DOS). In order to explore transport properties in MTJs, the density of scattering states (DOSS) was studied from the point of band symmetry. It has been found that CoFe|tungsten interface blocks scattering states transmission in the anti-parallel condition. This work reports TMR and transport properties in MTJs with different capping layers, and proves that tungsten is a proper capping layer material, which would benefit the design and optimization of MTJs.Since the discovery of tunnel magnetoresistance (TMR) in the Fe|Ge-oxide|Co trilayer structure, 1 the TMR effect has become the significant principle of non-volatile magnetic random access memory (MRAM). 2 As the basic element of MRAM, magnetic tunnel junction (MTJ) was investigated in detail. 3 Thanks to rapid advances in growth technique of ultra-thin ferromagnetic films, CoFeB|MgO MTJs with high TMR ratio have been achieved 4-7 as predicted by ab initio calculations. 8 Recently, based on MTJs with high TMR and the spin transfer torque effect, the spin-transfer-torque MRAM (STT-MRAM) is achieved with merits of high density and low power consumption. 9 _______________________________________ a) Electronic

show abstract

Perpendicular magnetic tunnel junction (p-MTJ) spin-valves designed with a top Co2Fe6B2 free layer and a nanoscale-thick tungsten bridging and capping layer

Cited by 22 publications

References 36 publications

Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistance

Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistance

Modulation of Heavy Metal/Ferromagnetic Metal Interface for High‐Performance Spintronic Devices

Large influence of capping layers on tunnel magnetoresistance in magnetic tunnel junctions

Contact Info

Product

Resources

About