X-ray photoemission study of CoFeB∕MgO thin film bilayers

Read, J.C.; Mather, P. G.; Buhrman, R. A.

doi:10.1063/1.2717091

Cited by 93 publications

(79 citation statements)

References 12 publications

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“…4 as a function of sput- Further analyzing the peak position in Fig. 3͑a͒, we can find that the position of B oxide between 22 and 24 min sputtering time is almost constant and shifted by about 1 eV to higher BE compared with the B oxide position in the reference sample, which agrees with the results of Read et al 7 The higher BE means that the B in MgO is in a higher oxidation state, closer to B 3+ , than B of the boron oxide in the oxidized CoFeB layer ͑BO x ͒. This B 1s position in MgO also agrees with the value measured by Ong et al 19 on B 2 O 3 ͑Ϫ193.6 eV with respect to the Fermi level͒.…”

Section: B Boron Distribution In the Mgo Barriersupporting

confidence: 81%

“…It leads to two possibilities: ͑i͒ B could be in a substitutional position, occupying the Mg vacancies to form a ͑MgO͒ x ͑B 2 O 3 ͒ y compound 11 or ͑ii͒ it could be in the amorphous form of B 2 O 3 localized in the MgO grain boundaries. The large concentration of B distributed in our MgO layer after annealing agrees both with the claims of Read et al 7 that an intermediate oxide Mg x B y O could form after the annealing procedure and with the recent study of boron distribution by Cha et al by using EELS. 11 However, to end up this discussion, further experiments are required.…”

Section: B Defects In the Mgo Barriersupporting

confidence: 80%

“…In fact, Read et al 7 and Cha et al 8 have found that B diffusion is very dependent on the growth method. B diffusion is more pronounced in rf-sputtered MgO layers than for e-beam evaporated MgO.…”

Section: B Defects In the Mgo Barriermentioning

confidence: 99%

“…[6][7][8][9][10][11][12][13][14][15][16] However, different conclusions came out from the experiments. Some groups reported that a considerable quantity of B diffuse into the MgO barrier after annealing, [6][7][8][9][10][11] while some others observed that boron tends to segregate at the MgO/CoFeB interface and form BO x after the crystallization of CoFeB layer. [12][13][14][15] Moreover, recently, the group of Miyajima et al 16 found that the crystallization of CoFeB layers was strongly dependent on the capping materials.…”

Section: Introductionmentioning

confidence: 99%

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Depth analysis of boron diffusion in MgO/CoFeB bilayer by x-ray photoelectron spectroscopy

Lü

Lépine

Jézéquel

et al. 2010

Journal of Applied Physics

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We have studied the boron ͑B͒ diffusion in MgO/CoFeB bilayer by x-ray photoelectron spectroscopy depth analysis. A large concentration of B ͑B / Mg= 0.16͒ was found to diffuse into the MgO barrier after 350°C annealing. The boron in MgO is in a highly oxidized B 3+ state and is homogenously distributed in the whole barrier. The important B diffusion in MgO could be related to the CoFeB crystallization process which begins from the under CoFeB/Ru interface and pushes boron atoms to diffuse into the MgO barrier during annealing.

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Section: B Boron Distribution In the Mgo Barriersupporting

confidence: 81%

Section: B Defects In the Mgo Barriersupporting

confidence: 80%

Section: B Defects In the Mgo Barriermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Depth analysis of boron diffusion in MgO/CoFeB bilayer by x-ray photoelectron spectroscopy

Lü

Lépine

Jézéquel

et al. 2010

Journal of Applied Physics

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“…In our experiment, during an annealing process the B atoms from CoFeB electrode can diffuse into the MgO barrier 15 ͑which is not the case in pure Fe electrodes used in experiment in Refs. 5 and 6͒, which can result in other exchange mechanisms.…”

Section: B Iecmentioning

confidence: 99%

Interlayer exchange coupling and current induced magnetization switching in magnetic tunnel junctions with MgO wedge barrier

Skowroński

Stobiecki

Wrona

et al. 2010

Journal of Applied Physics

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Current induced magnetization switching and interlayer exchange coupling (IEC) in sputtered CoFeB/MgO/CoFeB exchange-biased magnetic tunnel junctions with an extremely thin (0.96–0.62 nm) MgO wedge barrier is investigated. The IEC is found to be ferromagnetic for all samples and the associated energy increases exponentially down to a barrier thickness of 0.7 nm. Nanopillars with resistance area product ranging from 1.8 to 10 Ω μm2 and sizes of 0.13 μm2 down to 0.03 μm2 and tunneling magnetoresistance values of up to 170% were prepared. We found, that the critical current density increases with decreasing MgO barrier thickness. The experimental data and theoretical estimations show that the barrier thickness dependence of the spin transfer torque can largely be explained by a reduction in the tunnel current polarization at very small barrier thickness.

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Probing a Device's Active Atoms

et al. 2017

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Materials science and device studies have, when implemented jointly as "operando" studies, better revealed the causal link between the properties of the device's materials and its operation, with applications ranging from gas sensing to information and energy technologies. Here, as a further step that maximizes this causal link, the paper focuses on the electronic properties of those atoms that drive a device's operation by using it to read out the materials property. It is demonstrated how this method can reveal insight into the operation of a macroscale, industrial-grade microelectronic device on the atomic level. A magnetic tunnel junction's (MTJ's) current, which involves charge transport across different atomic species and interfaces, is measured while these atoms absorb soft X-rays with synchrotron-grade brilliance. X-ray absorption is found to affect magnetotransport when the photon energy and linear polarization are tuned to excite FeO bonds parallel to the MTJ's interfaces. This explicit link between the device's spintronic performance and these FeO bonds, although predicted, challenges conventional wisdom on their detrimental spintronic impact. The technique opens interdisciplinary possibilities to directly probe the role of different atomic species on device operation, and shall considerably simplify the materials science iterations within device research.

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X-ray photoemission study of CoFeB∕MgO thin film bilayers

Cited by 93 publications

References 12 publications

Depth analysis of boron diffusion in MgO/CoFeB bilayer by x-ray photoelectron spectroscopy

Depth analysis of boron diffusion in MgO/CoFeB bilayer by x-ray photoelectron spectroscopy

Interlayer exchange coupling and current induced magnetization switching in magnetic tunnel junctions with MgO wedge barrier

Probing a Device's Active Atoms

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