Surface acoustic wave induced modulation of tunneling magnetoresistance in magnetic tunnel junctions

Bhattacharya, Dhritiman; Sheng, Peng; Abeed, Ahsanul; Zhao, Zhengyang; Li, Hongshi; Wang, Jian Ping; Bandyopadhyay, Supriyo; Ma, Bin; Atulasimha, Jayasimha

doi:10.1063/5.0051905

Cited by 3 publications

References 49 publications

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Non-volatile Memory Implemented with Straintronic Magnetic Tunnel Junctions

Bandyopadhyay

2022

Magnetic Straintronics

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The straintronic magnetic tunnel junction (s-MTJ) is an MTJ whose resistance state can be changed continuously or gradually from high to low with a gate voltage that generates strain the magnetostrictive soft layer. This unusual feature, not usually available in MTJs that are switched abruptly with spin transfer torque, spin-orbit torque or voltage-controlled-magnetic-anisotropy, enables many analog applications where the typically low tunneling magneto-resistance ratio of MTJs (on/off ratio of the switch) and the relatively large switching error rate are not serious impediments unlike in digital logic or memory. More importantly, the transfer characteristic of a s-MTJ (conductance versus gate voltage) always sports a linear region that can be exploited to implement analog arithmetic, vector matrix multiplication and linear synapses in deep learning networks very effectively. In these applications, the s-MTJ is actually superior to the better known memristors and domain wall synapses which do not exhibit the linearity and/or the analog behavior.

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Non-volatile Memory Implemented with Straintronic Magnetic Tunnel Junctions

Bandyopadhyay

2022

Magnetic Straintronics

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Effects of surface acoustic waves on reversal of magnetic domains in patterned films with perpendicular magnetic anisotropy

Li,

Liu,

Qiao

et al. 2024

Applied Physics Letters

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In this work, the magnetization reversal of patterned Pt/Co/Pt multilayers influenced by surface acoustic waves is investigated. For each patterned cell, the magnetization reversal involves formation of a reversal nucleus followed by rapid motion of a domain wall. The nucleation probability of the reversal nucleus increases with the power of the applied surface acoustic wave, which is explained by the magnetic droplet model, and fitting the experimental results with this model gives important parameters such as the domain-wall energy density and the reduction rate of local perpendicular anisotropy. The fitting results for different patterned cells are consistent with the experimental results, which validates this model for dealing with such issues.

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Influence of surface acoustic wave (SAW) on nanoscale in-plane magnetic tunnel junctions

Zink,

Ma,

Zhang

et al. 2024

AIP Advances

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The use of voltage induced strain to switch magnetic tunnel junctions (MTJs) is a promising solution for reducing the switching energy in MRAM technologies. The MTJ is integrated with a piezoelectric layer to generate the strain. A very thin layer is needed to switch with small voltages and small energy dissipation. It is challenging to synthesize ultrathin piezoelectric layers that retain a high degree of piezoelectricity. An alternate approach is to use time-varying strain generated by a surface acoustic wave (SAW). This approach does not require a thin piezoelectric layer since the SAW is confined to the surface of the layer. In this study, we fabricated in-plane MTJs on piezoelectric LiNbO3 substrates and used IDTs to generate the SAW signal within the substrate. Our results showed that the SAW signal had a significant influence on the resistance and the tunneling magnetoresistance (TMR) ratio of the MTJs. The influence was much less significant in nanometer size MTJs than in micrometer sized ones. Most surprisingly, the SAW signal caused the tunneling magnetoresistance ratio (TMR) to drop below zero for the micrometer size MTJ, meaning that the antiparallel resistance RAP is temporarily less than the parallel resistance RP under SAW excitation. Our results provide insight into the dynamic behavior of MTJs under periodic strain and the dependence of this behavior on the device dimensions as they are scaled down to nanometer sizes.

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Surface acoustic wave induced modulation of tunneling magnetoresistance in magnetic tunnel junctions

Cited by 3 publications

References 49 publications

Non-volatile Memory Implemented with Straintronic Magnetic Tunnel Junctions

Non-volatile Memory Implemented with Straintronic Magnetic Tunnel Junctions

Effects of surface acoustic waves on reversal of magnetic domains in patterned films with perpendicular magnetic anisotropy

Influence of surface acoustic wave (SAW) on nanoscale in-plane magnetic tunnel junctions

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