Basic principles of STT-MRAM cell operation in memory arrays

Khvalkovskiy, A. V.; Apalkov, Dmytro; Watts, Steven; Chepulskii, Roman V.; Beach, R. S.; Ong, A.; Tang, X.; Driskill-Smith, A.; Butler, W. H.; Visscher, P. B.; Lottis, D. K.; Chen, E; Nikitin, V.; Krounbi, M.

doi:10.1088/0022-3727/46/7/074001

Cited by 466 publications

(348 citation statements)

References 97 publications

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“…Prominent examples for such devices are spin-transfer torque magnetic random-access memories (STT MRAM) [1,2,3] and spin-torque oscillators (STO) that serve as field generators for microwave assisted recording of hard-disk drives [4,5].…”

Section: Introductionmentioning

confidence: 99%

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

et al. 2017

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We investigate the spin-transfer torque in a magnetic multilayer structure by means of a spin-diffusion model. The torque in the considered system, consisting of two magnetic layers separated by a conducting layer, is caused by a perpendicular-to-plane current. We compute the strength of the field-like and the damping-like torque for different material parameters and geometries. Our studies suggest that the field-like torque highly depends on the exchange coupling strength of the itinerant electrons with the magnetization both in the pinned and the free layer. While a low coupling leads to very high field-like torques, a high coupling leads to low or even negative field-like torques. The dependence of the different torque terms on system parameters is considered very important for the development of applications such as STT MRAM and spin-torque oscillators.

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Section: Introductionmentioning

confidence: 99%

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

et al. 2017

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confidence: 99%

“…[1][2][3] Traditionally, these systems have been formed by in-plane (IP) materials with the anisotropy arising from the shape of patterned structures. 2 Aiming to move towards higher densities, IP materials are being substituted by films with high perpendicular magnetic anisotropy (PMA), which have high thermal stability and sharp magnetic switching. [2][3][4] Recently, in order to reduce the critical current density of spin-transfer-torque MRAM, alternative magnetic systems which combine IP and PMA materials have been proposed.…”

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confidence: 99%

“…2 Aiming to move towards higher densities, IP materials are being substituted by films with high perpendicular magnetic anisotropy (PMA), which have high thermal stability and sharp magnetic switching. [2][3][4] Recently, in order to reduce the critical current density of spin-transfer-torque MRAM, alternative magnetic systems which combine IP and PMA materials have been proposed. 2,3 Furthermore, systems where the magnetization of one of the magnetic electrodes is canted, forming non-collinear magnetic configurations between layers, should reduce substantially the writing energy of these devices.…”

mentioning

confidence: 99%

“…[2][3][4] Recently, in order to reduce the critical current density of spin-transfer-torque MRAM, alternative magnetic systems which combine IP and PMA materials have been proposed. 2,3 Furthermore, systems where the magnetization of one of the magnetic electrodes is canted, forming non-collinear magnetic configurations between layers, should reduce substantially the writing energy of these devices. [5][6][7] These last systems can be realized using asymmetric SAFs, where fine control of the effective anisotropy of the layers and the coupling between them is required.…”

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confidence: 99%

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Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition

Fernández-Pacheco

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Mansell

et al. 2014

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We have designed a bilayer synthetic antiferromagnet where the order of layer reversal can be selected by varying the sweep rate of the applied magnetic field. The system is formed by two ultra-thin ferromagnetic layers with different proximities to the spin reorientation transition, coupled antiferromagnetically using Ruderman-Kittel-Kasuya-Yosida interactions. The different dynamic magnetic reversal behavior of both layers produces a crossover in their switching fields for field rates in the kOe/s range. This effect is due to the different effective anisotropy of both layers, added to an appropriate asymmetric antiferromagnetic coupling between them. Field-rate controlled selective switching of perpendicular magnetic anisotropy layers as shown here can be exploited in sensing and memory applications.

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Magnetic Tunnel Junctions for Spintronics: Principles and Applications

Peng

Zhang

Wang

et al. 2014

Wiley Encyclopedia of Electrical and Electronics Engineering

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Spintronics has received a great attention and considerable interest within the past decades. As a core device in this discipline, magnetic tunnel junction (MTJ) evolved rapidly and already be used in applications such as hard disk drive (HDD) read head and magnetic random access memory (MRAM) etc. In this article, we review some basic effects related to MTJ, for example, giant magnetoresistance (GMR), tunnel magnetoresistance (TMR) and spin transfer torque (STT). Based on these theories, two kinds of MTJs, in‐plane and perpendicular MTJs, are introduced. Then, several magnetization switching methods, which include field‐induced switching, thermally assisted switching, STT switching and recent voltage‐controlled switching, are proposed. In the end, some important applications of MTJs are presented.

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Basic principles of STT-MRAM cell operation in memory arrays

Cited by 466 publications

References 97 publications

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

Dynamic selective switching in antiferromagnetically-coupled bilayers close to the spin reorientation transition

Magnetic Tunnel Junctions for Spintronics: Principles and Applications

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