Magnetic Tunnel Junctions with Ferroelectric Barriers: Prediction of Four Resistance States from First Principles

Velev, Julian P.; Duan, Chun‐Gang; Burton, John; Smogunov, Alexander; Niranjan, Manish K.; Tosatti, Erio; Jaswal, S. S.; Tsymbal, Evgeny Y.

doi:10.1021/nl803318d

Cited by 310 publications

(289 citation statements)

References 45 publications

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“…The TER associated with ferroelectric polarization switching has been observed experimentally in BaTiO 3 -and PbTiO 3 -based FTJs in which either La 2/3 Sr 1/3 MnO 3 or SrRuO 3 is used as one of the electrodes while the other side of the ferroelectric thin film is in contact with the tip of an atomic force microscope [24][25][26] . The predicted simultaneous TMR and TER effects 23 have also been demonstrated experimentally in La 2/3 Sr 1/3 MnO 3 /BaTiO 3 /Fe (or Co) MFTJs [27][28][29][30][31][32][33][34] . Although the majority of the work deals with low bias, the existence of TER at finite bias has been predicted based on calculations using a semiclassical approximation 19 and first-principles 35 in FTJs, and model tight-binding calculations in MFTJs 36 .…”

Section: Introductionsupporting

confidence: 64%

“…Model predictions [18][19][20][21] and ab initio calculations 22,23 of FTJs and MFTJs show that the reversal of the electric polarization of the ferroelectric barrier can produce a sizable change in the resistance, the so-called tunnelling electroresistance (TER). The effect occurs at zero bias provided that the junction is asymmetric, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

et al. 2015

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Based on model calculations we predict electric-field control of the spin transfer torque (STT) in magnetic tunnel junctions with ferroelectric barriers. We demonstrate that the bias dependence of the in-plane, T , and out-of-plane, T ⊥ , components of the STT can be dramatically modified by the ferroelectric polarization. In particular, the magnitude of the STT can be enhanced or suppressed by switching the polarization direction and in some cases the sign of STT can be toggled. The underlying mechanism is the combination of polarization-induced symmetry breaking and the interplay of the bias-induced and polarization-induced spin-dependent screening giving rise to a rich behavior of the electrostatic potential energy profile. These properties could lead to enhanced switching efficiency in STT-based devices and open a new avenue for applications of multiferroic devices.

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Section: Introductionsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

et al. 2015

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“…In MFTJs, the TER and TMR effects coexist, as was first predicted by Zhuravlev et al [172]. Therefore, MFTJs represent a four-state resistance device where resistance can be switched by both electric and magnetic fields [28,173,174].…”

Section: (B) Multi-ferroic Tunnel Junctionsmentioning

confidence: 67%

“…In MFTJs with asymmetric interfaces (electrodes), this could lead to electric-field control of TMR. Indeed, four resistance states have been predicted from transport calculations of SrRuO 3 /BaTiO 3 /SrRuO 3 MFTJs [28]. Here, the TMR effect has the same origin as in ordinary MTJs [8,181].…”

Section: (B) Multi-ferroic Tunnel Junctionsmentioning

confidence: 86%

Multi-ferroic and magnetoelectric materials and interfaces

Velev

Jaswal

Tsymbal

2011

Phil. Trans. R. Soc. A.

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204

144

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The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.

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“…An ultrathin barrier results in a large tunneling current, which facilitates easy signal readout and device scaling. However, serious undesirable effects, including the FE dead layer, 22 pinned interface dipole, [23][24][25] and leakage current, 11,18,26 arise and degrade the device performance.…”

mentioning

confidence: 99%

Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO₃/SrTiO₃ Composite Barriers

et al. 2016

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ABSTRACT:Ferroelectric tunnel junctions (FTJs) have attracted increasing research interest as a promising candidate for non-volatile memories. Recently, significant enhancements of tunneling electroresistance (TER) have been realized through modifications of electrode materials.However, direct control of the FTJ performance through modifying the tunneling barrier has not been adequately explored. Here, adding a new direction to FTJ research, we fabricated FTJs with Ferroelectric tunnel junctions (FTJs), composed of a thin ferroelectric (FE) layer sandwiched in between two metallic electrodes, have been intensively investigated in recent years. This device is considered to be a promising candidate for next-generation nonvolatile memories, because it combines the advantages of both ferroelectric random-access-memory and resistiveswitching memory. 1-3 The concept of FTJ was first proposed by Esaki in 1971, 4 but the research activities have not flourished untixl this decade. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] The operation of FTJs has been mainly explained in terms of interfacial screening of polarization charges. [5][6][7][8] In a metal 1(M1)/FE/metal 2 (M2) structured FTJ (Figure 1a), the two asymmetric electrodes lead to unequal screen lengths and potential changes at metal/FE interfaces. Depending on the polarizations, the electrostatic potential profile of tunneling barrier will be varied. As a result, the tunneling resistance can be switched between low (ON) and high (OFF) values by polarization reversal, leading to the socalled tunneling electroresistance (TER) effect.Extensive experimental works based on this asymmetric screening scenario have been reported during the last decade. In 2009, the TER effect was first demonstrated using conducting atomic force microscopy (CAFM). 9-11 Subsequently, FTJs with highly reproducible performance were realized in capacitor geometry, which will be useful for practical applications. 12,13 Up to recently, most studies of FTJs have focused on improving device performance by modifying the electrode materials. [14][15][16][17][18][19][20] Typical examples include the use of lightly doped semiconductors, [14][15][16] For a thick barrier, these obstacles can be avoided, but the tunneling current becomes too small for realizing a practically useful device. As an alternative, several groups have theoretically proposed a new kind of FTJ using an FE/paraelectric (FE/PE) composite barrier. 27,28 The PE layer provides a new route to control the tunneling barrier potentials, and thus the TER can be tuned and significantly enhanced. However, there have been few experimental efforts to systematically attest this theoretical prediction. 29 In this paper, we report experimental control of the TER effect by directly manipulating the tunneling barrier thickness and composition. For this purpose, we fabricated two types of FTJs: Figure S5), which further confirm good epitaxial film qualities.We estimated the lattice constants of the oxide layers from XRD reci...

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Magnetic Tunnel Junctions with Ferroelectric Barriers: Prediction of Four Resistance States from First Principles

Cited by 310 publications

References 45 publications

Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

Multi-ferroic and magnetoelectric materials and interfaces

Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO₃/SrTiO₃ Composite Barriers

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Magnetic Tunnel Junctions with Ferroelectric Barriers: Prediction of Four Resistance States from First Principles

Cited by 310 publications

References 45 publications

Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

Multi-ferroic and magnetoelectric materials and interfaces

Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO3/SrTiO3 Composite Barriers

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Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO₃/SrTiO₃ Composite Barriers