Predictive modelling of ferroelectric tunnel junctions

Velev, Julian P.; Burton, John; Zhuravlev, M. Ye.; Tsymbal, Evgeny Y.

doi:10.1038/npjcompumats.2016.9

Cited by 98 publications

(76 citation statements)

References 98 publications

(144 reference statements)

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“…This property is sustained down to the nanoscale dimensions [2][3][4], which makes ferroelectrics attractive for modern technological applications, such as nonvolatile random access memories and field sensors [5]. Nanoscale ferroelectrics found an important application in ferroelectric tunnel junctions (FTJs) [6][7][8]. A FTJ consists of two metal or semiconductor electrodes separated by a nanometer-thick ferroelectric barrier layer.…”

Section: Introductionmentioning

confidence: 99%

Resonant tunneling across a ferroelectric domain wall

Tao

Velev

et al. 2018

Phys. Rev. B

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Li, M.; Tao, L. L.; Velev, J. P.; and Tsymbal, Evgeny Y., "Resonant tunneling across a ferroelectric domain wall" (2018 Motivated by recent experimental observations, we explore electron transport properties of a ferroelectric tunnel junction (FTJ) with an embedded head-to-head ferroelectric domain wall, using first-principles density-functional theory calculations. We consider a FTJ with La 0.5 Sr 0.5 MnO 3 electrodes separated by a BaTiO 3 barrier layer and show that an in-plane charged domain wall in the ferroelectric BaTiO 3 can be induced by polar interfaces. The resulting V-shaped electrostatic potential profile across the BaTiO 3 layer creates a quantum well and leads to the formation of a two-dimensional electron gas, which stabilizes the domain wall. The confined electronic states in the barrier are responsible for resonant tunneling as is evident from our quantum-transport calculations. We find that the resonant tunneling is an orbital selective process, which leads to sharp spikes in the momentum-and energy-resolved transmission spectra. Our results indicate that domain walls embedded in FTJs can be used to control the electron transport.

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Section: Introductionmentioning

confidence: 99%

Resonant tunneling across a ferroelectric domain wall

Tao

Velev

et al. 2018

Phys. Rev. B

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“…This asymmetry is known to appear as a result of different screening lengths and/or work functions of the electrodes or different interface terminations, leading to the TER effect. 3 To illustrate the effect of asymmetry, we assume that a FTJ has FM and NM electrodes with different work functions, resulting in a built-in electric field. This electric field, pointing in a fixed direction, is expected to affect the SOC parameters when the FE polarization is reversed and thus to change TAMR.…”

Section: (%)mentioning

confidence: 99%

Tunneling Anisotropic Magnetoresistance in Ferroelectric Tunnel Junctions

2019

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Using a simple quantum-mechanical model, we explore a tunneling anisotropic magnetoresistance (TAMR) effect in ferroelectric tunnel junctions (FTJs) with a ferromagnetic electrode and a ferroelectric barrier layer, which spontaneous polarization gives rise to the Rashba and Dresselhaus spin-orbit coupling (SOC). For realistic parameters of the model, we predict sizable TAMR measurable experimentally. For asymmetric FTJs, which electrodes have different work functions, the built-in electric field affects the SOC parameters and leads to TAMR dependent on ferroelectric polarization direction. The SOC change with polarization switching affects tunneling conductance, revealing a new mechanism of tunneling electroresistance (TER). These results demonstrate new functionalities of FTJs which can be explored experimentally and used in electronic devices.

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“…[2]. This has been demonstrated through tunnel electro-resistance (TER), which can be described by the Brinkman model using the barrier height of the insulator and the screening length of the electrodes [3][4][5]. The change in resistance scales with the fraction of ferroelectric polarization domains, from which a parallel conduction model of ferroelectric poled up and down domains has been proposed [6].…”

Section: I．introductionmentioning

confidence: 99%

Nonvolatile Multilevel States in Multiferroic Tunnel Junctions

Fang

Zhang

et al. 2019

Phys. Rev. Applied

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Manipulation of tunneling spin-polarized electrons via a ferroelectric interlayer sandwiched between two ferromagnetic electrodes, dubbed Multiferroic Tunnel Junctions (MFTJs), can be achieved not only by the magnetic alignments of two ferromagnets but also by the electric polarization of the ferroelectric interlayer, providing great opportunities for next-generation multi-state memory devices. Here we show that a La0.67Sr0.33MnO3 (LSMO)/PbZr0.2Ti0.8O3(PZT)/Co structured MFTJ device can exhibit multilevel resistance states in the presence of gradually reversed ferroelectric domains via tunneling electroresistance and tunneling magnetoresistance, respectively. The nonvolatile ferroelectric control in the MFTJ can be attributed to separate contributions arising from two independent ferroelectric channels in the PZT interlayer with opposite polarization. Our study shows the dominant role of 'mixed' ferroelectric states on achieving accumulative electrical modulation of multilevel resistance states in MFTJs, paving the way for multifunctional device applications.

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Predictive modelling of ferroelectric tunnel junctions

Cited by 98 publications

References 98 publications

Resonant tunneling across a ferroelectric domain wall

Resonant tunneling across a ferroelectric domain wall

Tunneling Anisotropic Magnetoresistance in Ferroelectric Tunnel Junctions

Nonvolatile Multilevel States in Multiferroic Tunnel Junctions

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