Effect of spin-dependent screening on tunneling electroresistance and tunneling magnetoresistance in multiferroic tunnel junctions

Zhuravlev, M. Ye.; Maekawa, Sadamichi; Tsymbal, Evgeny Y.

doi:10.1103/physrevb.81.104419

Cited by 93 publications

(76 citation statements)

References 42 publications

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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: 79%

Multi-ferroic and magnetoelectric materials and interfaces

Velev

Jaswal

Tsymbal

2011

Phil. Trans. R. Soc. A.

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208

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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Section: (B) Multi-ferroic Tunnel Junctionsmentioning

confidence: 79%

Multi-ferroic and magnetoelectric materials and interfaces

Velev

Jaswal

Tsymbal

2011

Phil. Trans. R. Soc. A.

Self Cite

208

144

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“…Theoretical works on MTJs with ferroelectric insulating barrier 27 predict that the orientation of the electric polarisation can influence the electron density of states at the ferromagnetic/ insulator interfaces and modify the asymmetry between majority and minority electrons. Such modification implies a change in the spin polarisation of the tunnelling electrons and should therefore show up in TMR properties.…”

Section: Discussionmentioning

confidence: 99%

Size-induced enhanced magnetoelectric effect and multiferroicity in chromium oxide nanoclusters

et al. 2014

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The control of the magnetization of a material with an electric field would make the design and the integration of novel electronic devices possible. This explains the renewed interest in multiferroic materials. Progress in this field is currently hampered by the scarcity of the materials available and the smallness of the magnetoelectric effects. Here we present a proofof-principle experiment showing that engineering large strains through nanoscale size reduction is an efficient route for increasing magnetoelectric coefficients by orders of magnitude. The archetype magnetoelectric material, Cr 2 O 3 , in the form of epitaxial clusters, exhibits an unprecedented 600% change in magnetization magnitude under 1 V. Furthermore, a multiferroic phase, with both magnetic and electric spontaneous polarizations, is found in the clusters, while absent in the bulk.

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“…The virtue of the free electron approach is to reduce the complexity of the band structure to a minimal set of parameters relevant to the spin transport, providing a qualitative description of the physics at stake. This method successfully predicted the gigantic TER effect by Zhuravlev et al [21,38] as well as the bias dependence of the spin torque in magnetic tunnel junctions [13,14,17]. Strictly speaking, this formalism applies in low band filling systems where the tunneling is dominated by electrons close to the point.…”

mentioning

confidence: 90%

Controlling the spin-torque efficiency with ferroelectric barriers

2015

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KAUST RepositoryNonequilibrium spin-dependent transport in magnetic tunnel junctions comprising a ferroelectric barrier is theoretically investigated. The exact solutions of the free electron Schrödinger equation for electron tunneling in the presence of interfacial screening are obtained by combining Bessel and Airy functions. We demonstrate that the spin transfer torque efficiency, and more generally the bias dependence of tunneling magneto-and electroresistance, can be controlled by switching the ferroelectric polarization of the barrier. In particular, the critical voltage at which the in-plane torque changes sign can be strongly enhanced or reduced depending on the direction of the ferroelectric polarization of the barrier. This effect provides a supplementary way to electrically control the current-driven dynamic states of the magnetization and related magnetic noise in spin transfer devices. The electrical control of magnetization in thin films is currently attracting intensive efforts due to its major potential for applications [1]. Current-and voltage-induced magnetization dynamics have been observed in a wide variety of magnetic heterostructures such as metallic and semiconducting spin valves and domain walls [2][3][4][5]. Of most technological interest is the manipulation of magnetization in magnetic tunnel junctions (MTJs)-trilayers comprising a tunnel barrier embedded between two ferromagnets-by means of either gate voltages or spin-polarized currents. In the first case, a large voltage pulse is applied across the barrier and charge reordering at the interface modifies the interfacial magnetic anisotropy [5]. In the second case, a spin-polarized current tunnels through the barrier and transfers its spin angular momentum to the local magnetization of the free magnetic layer [2][3][4]. This last phenomenon, known as spin transfer torque [6], enables the design of promising components such as on-chip tunable microwave generators [7], magnetic memory cells [8], race-track memories [9], and so on.The most successful candidates to date that combine low critical switching current densities with large tunneling magnetoresistance ratios (TMR) are MTJs based on MgO barriers and transition metal electrodes [10] (i.e., Fe, Co, Ni, and their compounds). Significant progress has been achieved towards understanding the complex microscopic nature of the junction's interfaces [11,12] and establishing the characteristics of spin transfer torque [13,14]. Despite undeniable successes [15,16], the actual exploitation of spin transfer torque in devices is facing major hurdles, among which the necessary reduction of its critical switching current as well as the control of current-driven magnetic instabilities. Serious efforts are being made towards improving the device performances, and solutions such as engineering the junction structural asymmetries [17] or designing the metallic electrodes stacking [18] have been proposed to enhance the device * aurelien.manchon@kaust.edu.sa operation through modifying the bias depende...

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Effect of spin-dependent screening on tunneling electroresistance and tunneling magnetoresistance in multiferroic tunnel junctions

Cited by 93 publications

References 42 publications

Multi-ferroic and magnetoelectric materials and interfaces

Multi-ferroic and magnetoelectric materials and interfaces

Size-induced enhanced magnetoelectric effect and multiferroicity in chromium oxide nanoclusters

Controlling the spin-torque efficiency with ferroelectric barriers

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