230% room temperature magnetoresistance in CoFeB/MgO/CoFeB magnetic tunnel junctions

Djayaprawira, D.D.; Tsunekawa, K.; Nagai, M.; Maehara, H.; Yamagata, S.; Watanabe, Naoki; Yuasa, Shinji; Ando, Kazunori

doi:10.1109/intmag.2005.1463662

Cited by 23 publications

(23 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This value is in excellent agreement with E m = 200 ± 10 meV deduced from the Arrhenius of n x for that system [254,255] and with E m = 200 ± 30 meV measured with low-T AFM by integrating the force needed to displace the atoms over the bridge site times the distance [256]. The attempt frequency had to be set to ν 0 = 1.5 × 10 15 Hz, which is quite high compared with the common value of ν 0 = 10 13 Hz, but it is close to the value of ν 0 = 1 × 10 14±0.5 Hz found from the density scaling [255]. The following step from s = 2.5 to 4.5 atoms at 95 K gives a dimer diffusion barrier of E m,2 = 270 ± 30 meV.…”

Section: The Smoluchowski Ripeningsupporting

confidence: 82%

“…Another order of magnitude was achieved in 2004 when 188% TMRs were reported for fully epitaxial Fe/MgO(100)/Fe junctions [13] and 220% for polycrystalline FeCo/MgO/FeCoB junctions with (001) texture [14]. In 2005, finally, 230% for CoFeB/MgO(100)/CeFeB junctions with polycrystalline ferromagnets, facilitating the fabrication of junctions with uniform and reproducible properties [15]. The current room-temperature record is 410% and realized in fully epitaxial Co(100)/MgO(100)/Co(100) junctions [16].…”

Section: Introduction 423mentioning

confidence: 99%

See 1 more Smart Citation

Epitaxial Growth of Thin Films

Brune

2014

Surface and Interface Science

View full text Add to dashboard Cite

This chapter gives an introduction to the epitaxial growth of thin films on solid substrates. The term epitaxy refers to the growth of a crystalline layer on (epi) the surface of a crystalline substrate, where the crystallographic orientation of the substrate surface imposes a crystalline order (taxis) onto the thin film. This implies that film elements can be grown, up to a certain thickness, in crystal structures differing from their bulk. If film and substrate have the same crystal lattices, but different lattice constants, the film will be under strain, that is, it will have a slightly different lattice constant than in its own bulk. Both effects, together with the electronic hybridization at the interface, lead to novel properties.One distinguishes homo-and heteroexpitaxy, where the former refers to the growth on one element on a crystal surface of its own and the latter refers to the more general case, where film and substrate materials are different. Note that the first distinguishes itself from crystal growth, as we will see in more detail later.We start this chapter by giving examples from technology, illustrating where thin epitaxial films are used and outlining potential applications that become reality once we are able to grow the respective thin film sequences. We then contrast thin film and crystal growth, respectively, with kinetics and thermodynamics of growth. We introduce the deposition techniques used in epitaxial thin film growth and then discuss the classical thermodynamic approach, which led to the definition of the growth modes. These modes refer to the morphology taken on by a system grown close to thermodynamic equilibrium. Often films are grown far away from equilibrium and their morphology is determined by kinetics, that is, it is the result of the microscopic path taken by the system during growth. This path is determined by the hierarchy of rates of the single atom, cluster or molecular precursor displacements as compared to the deposition rate. Owing to the importance of kinetics, we focus in the rest of the chapter on the kinetic description of growth. In order to simplify the topic, we start with coverages below one atomic layer that is referred to as a monolayer. The first submonolayer part will be on nucleation, followed by a discussion of island shapes that, very much like snowflakes, tell us about the elementary processes that took place during their formation. We then discuss island coarsening, either by evaporation of atoms from their edges, referred to as the Ostwald ripening, or by the diffusion and subsequent coalescence of entire islands, referred to as the

show abstract

Section: The Smoluchowski Ripeningsupporting

confidence: 82%

Section: Introduction 423mentioning

confidence: 99%

Epitaxial Growth of Thin Films

Brune

2014

Surface and Interface Science

View full text Add to dashboard Cite

show abstract

“…Soon after tunnel magnetoresistance (TMR) ratios over 1000% were theoretically predicted in the magnetic tunnel junctions (MTJs) with a crystalline (100) Fe/MgO/Fe structure by preferential tunneling of "half-metallic" ∆ 1 symmetry states 1,2 , TMR ratios ranging from 80 -355% at room temperature (RT) was experimentally demonstrated for fully (100) oriented epitaxial Fe/MgO/Fe MTJs 3,4 and sputter-deposited highly (100) oriented Fe(CoB)/MgO/Fe(CoB) MTJs [6][7][8] . The highest TMR ratio so far reported reaches 361 % for a sputter-deposited CoFeB/MgO/CoFeB structure 9 and 410 % for an epitaxial Co/MgO/Co structure.…”

mentioning

confidence: 99%

Effect of high annealing temperature on giant tunnel magnetoresistance ratio of CoFeB∕MgO∕CoFeB magnetic tunnel junctions

Hayakawa

Ikeda

Lee

et al. 2006

Applied Physics Letters

220

112

View full text Add to dashboard Cite

We report tunnel magnetoresistance (TMR) ratios as high as 472% at room temperature and 804% at 5 K in pseudo-spin valve (SV) CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) annealed at 450 o C, which is approaching the theoretically predicted value. By contrast, the TMR ratios for exchange-biased (EB) SV MTJs with a MnIr antiferromagnetic layer are found to drop when they are annealed at 450 o C.Energy dispersive X-ray analysis shows that annealing at 450 o C induces interdiffusion of Mn and Ru atoms into the MgO barrier and ferromagnetic layers in EB-SV MTJs.Mechanisms behind the different annealing behavior are discussed.

show abstract

“…Especially in crystalline systems tunnelling probabilities strongly depend on the symmetry of the involved states and the properties of interface states. These results have been substantiated by reports of ever increasing TMR ratios in (partly) crystalline systems Djayaprawira et al (2005), Ikeda et al (2008), Parkin et al (2004), and Yuasa et al (2004).…”

Section: Tunnelling Magnetoresistancesupporting

confidence: 71%

“…Very high TMR ratios are reported in MTJs with monocrystalline and epitaxial layers (Djayaprawira et al, 2005;Ikeda et al, 2008;Parkin et al, 2004;Yuasa et al, 2004). The measured TMR ratios exceed the theoretical maxima based on simple tunnel barrier models and confirm models that show the tunnelling conductance in epitaxial systems to be strongly dependent on the symmetry of the involved charge carrier states (Butler et al, 2001;Mathon and Umerski, 2001).…”

Section: Introductionsupporting

confidence: 63%

Spintronic effects at nickel-graphene interfaces

Geijn¹

View full text Add to dashboard Cite

230% room temperature magnetoresistance in CoFeB/MgO/CoFeB magnetic tunnel junctions

Cited by 23 publications

References 4 publications

Epitaxial Growth of Thin Films

Epitaxial Growth of Thin Films

Effect of high annealing temperature on giant tunnel magnetoresistance ratio of CoFeB∕MgO∕CoFeB magnetic tunnel junctions

Spintronic effects at nickel-graphene interfaces

Contact Info

Product

Resources

About