Disorder, defects, and band gaps in ultrathin (001) MgO tunnel barrier layers

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

doi:10.1103/physrevb.73.205412

Cited by 121 publications

(85 citation statements)

References 13 publications

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“…1a), we attribute this feature to tunnelling across the ground state of neutral/singly charged oxygen vacancies within the barrier (that is, F/F þ ). The spectral position and defect species assignment of this feature correspond quantitatively to that inferred from theoretical predictions 28 and scanning tunneling microscopy experiments 60 . We observe, however, that contrary to predictions 28 , the F/F þ centre does affect transmission in the AP state, as explained hereafter.…”

supporting

confidence: 52%

Localized states in advanced dielectrics from the vantage of spin- and symmetry-polarized tunnelling across MgO

et al. 2014

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Research on advanced materials such as multiferroic perovskites underscores promising applications, yet studies on these materials rarely address the impact of defects on the nominally expected materials property. Here, we revisit the comparatively simple oxide MgO as the model material system for spin-polarized solid-state tunnelling studies. We present a defect-mediated tunnelling potential landscape of localized states owing to explicitly identified defect species, against which we examine the bias and temperature dependence of magnetotransport. By mixing symmetry-resolved transport channels, a localized state may alter the effective barrier height for symmetry-resolved charge carriers, such that tunnelling magnetoresistance decreases most with increasing temperature when that state is addressed electrically. Thermal excitation promotes an occupancy switchover from the ground to the excited state of a defect, which impacts these magnetotransport characteristics. We thus resolve contradictions between experiment and theory in this otherwise canonical spintronics system, and propose a new perspective on defects in dielectrics.

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supporting

confidence: 52%

Localized states in advanced dielectrics from the vantage of spin- and symmetry-polarized tunnelling across MgO

et al. 2014

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“…In case of sputtered-grown MgO, Mg vacancy also plays an important role. 23 In addition, Choi et al 24 have also evidenced ionic oxygen interstitial defects in the sputtered MgO barrier. We have, therefore, checked the stoichiometry of our MgO barrier with nano-Auger depth analysis ͑not shown͒.…”

Section: B Defects In the Mgo Barriermentioning

confidence: 99%

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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“…Bulk -centers were studied extensively using optical spectroscopy [25]. Recently, -centers in thin MgO films were investigated using electron paramagnetic resonance [26] and scanning tunneling spectroscopy [27]. There is continuing theoretical interest in the physical properties of -centers in MgO in the bulk [28], [29] and on the surface [30].…”

Section: Vacancies In Mgomentioning

confidence: 99%