Spin-dependent tunnelling in magnetic tunnel junctions

Tsymbal, Evgeny Y.; Mryasov, O. N.; LeClair, P.

doi:10.1088/0953-8984/15/4/201

Cited by 586 publications

(449 citation statements)

References 181 publications

Supporting

Mentioning

413

Contrasting

Order By: Relevance

“…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]. The asymmetric interface termination (RuO 2 /BaO versus TiO 2 /SrO) creates a different polarization profile when the FE polarization is switched, producing the TER effect.…”

Section: (B) Multi-ferroic Tunnel Junctionsmentioning

confidence: 94%

Multi-ferroic and magnetoelectric materials and interfaces

Velev

Jaswal

Tsymbal

2011

Phil. Trans. R. Soc. A.

208

144

View full text Add to dashboard Cite

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.

show abstract

Section: (B) Multi-ferroic Tunnel Junctionsmentioning

confidence: 94%

Multi-ferroic and magnetoelectric materials and interfaces

Velev

Jaswal

Tsymbal

2011

Phil. Trans. R. Soc. A.

208

144

View full text Add to dashboard Cite

show abstract

“…This contrasts with the conclusion of recent work where the magnetoresistance observed in devices based on a variety of organic materials seemed to track the injection polarization 14 , which is explained in terms of the temperature dependence of the surface polarization of the ferromagnetic La 2/3 Sr 1/3 MnO 3 layer 24 . In our study, we avoided this by using a transition-metal ferromagnetic with a high Curie temperature for both of our injection electrodes, which ensures a weak variation of the spin injection efficiency in the experimental temperature range 25 . It is therefore unlikely that the abrupt change in the magnetoresistance of our devices at around 40 K is caused by the ferromagnetic electrodes.…”

Section: Quantitative Analysismentioning

confidence: 99%

Direct measurement of the electronic spin diffusion length in a fully functional organic spin valve by low-energy muon spin rotation

et al. 2008

View full text Add to dashboard Cite

Electronic devices that use the spin degree of freedom hold unique prospects for future technology. The performance of these 'spintronic' devices relies heavily on the efficient transfer of spin polarization across different layers and interfaces. This complex transfer process depends on individual material properties and also, most importantly, on the structural and electronic properties of the interfaces between the different materials and defects that are common to real devices. Knowledge of these factors is especially important for the relatively new field of organic spintronics, where there is a severe lack of suitable experimental techniques that can yield depth-resolved information about the spin polarization of charge carriers within buried layers of real devices. Here, we present a new depth-resolved technique for measuring the spin polarization of current-injected electrons in an organic spin valve and find the temperature dependence of the measured spin diffusion length is correlated with the device magnetoresistance.R ecently great efforts have been undertaken to use the spin degree of freedom in electronic devices. These activities are fuelled by the potential prospects of spin-electronic (or 'spintronic') devices for example in terms of increased processing speed and integration, non-volatility, reduced power consumption, multifunctionality and their suitability for quantum computing 1 . The most common method for using the spin in devices is based on the alignment of the electron spin ('up' or 'down') relative to either a reference magnetic field or the magnetization orientation of a ferromagnetic layer. Device operation normally proceeds with measuring a quantity such as the electrical current that depends on how the degree of spin alignment is transferred across the device. The so-called 'spin valve' is a prominent example of such a spin-enabled device that has already revolutionized hard-drive read heads and magnetic memory 1 . The efficient transfer of spin polarization in real device structures remains one of the most difficult challenges in spintronics, because it is dependent on more than just the properties of the individual materials that comprise the device.Recently 2,3 , the use of organic materials in spintronics has become of significant interest, primarily owing to their ease and small cost of processing and electronic and structural flexibility. Furthermore, the extremely long spin coherence times found in organic materials offer considerable advantages over other materials 3 . This favourable property is related to two factors, first the weak spin-orbit coupling of light elements such as carbon and second to the small nuclear hyperfine interaction 4,5 . The latter arises because the electron transport in π-conjugated molecules is normally confined to molecular states, delocalized to the carbon rings, the predominant isotope of which, 12 C, has zero nuclear spin 4 .A common way to measure spin diffusion is based on time-resolved optical techniques, where spin-polarized charge carrie...

show abstract

“…In particular, magnetic tunnel junctions (MTJs), consisting of two ferromagnetic metal layers separated by a thin insulating barrier layer, are the leading devices for field sensing, non-volatile magnetic random access memories (MRAMs), and spin logic applications [2][3][4] . Switching of the magnetization of one of the layers with respect to the other causes a large change in resistance, known as tunneling magnetoresistance (TMR) 5 . The switching is achieved either via an external magnetic field or a spin-polarized current which induces spin transfer torque (STT).…”

Section: Introductionmentioning

confidence: 99%

Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

et al. 2015

View full text Add to dashboard Cite

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.

show abstract

Spin-dependent tunnelling in magnetic tunnel junctions

Cited by 586 publications

References 181 publications

Multi-ferroic and magnetoelectric materials and interfaces

Multi-ferroic and magnetoelectric materials and interfaces

Direct measurement of the electronic spin diffusion length in a fully functional organic spin valve by low-energy muon spin rotation

Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

Contact Info

Product

Resources

About