In situ TEM studies of local transport and structure in nanoscale multilayer films

Chiaramonti, Ann N.; Thompson, L. J.; Egelhoff, William F.; Kabius, B.; Petford‐Long, Amanda K.

doi:10.1016/j.ultramic.2008.04.008

Cited by 11 publications

(12 citation statements)

References 51 publications

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“…39 Samples for in-situ electron holography experiments were prepared as described elsewhere. 36 Off-axis electron holography requires that the area of interest (in this case, the MgO barrier) must be close to the vacuum edge of the sample (several tens of nanometers, maximum). In order to meet this requirement, the sample was imaged (lightly etched) with a 5 kV Ga + ion beam in the FIB until the MgO was very near the exposed surface.…”

Section: Methodsmentioning

confidence: 99%

“…33 The interfacial roughness of Fe/MgO/Fe MTJs 34 and the segregation of B and O at the CoFeB/MgO interfaces in polycrystalline Mg-B-O 35 have been measured by a combination of electron energy loss spectroscopy (EELS) and scanning TEM (STEM) on the atomic scale. Recently, in-situ, site-specific electrical biasing TEM experiments were introduced 36 allowing direct correlation between the microstructure and transport behavior. 37,38 The chemical composition of the tunnel barrier and its interfaces with the electrodes are controlling factors in the spindependent tunneling effect needed for high TMR.…”

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confidence: 99%

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Effect of annealing and applied bias on barrier shape in CoFe/MgO/CoFe tunnel junctions

et al. 2011

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Energy-filtered transmission electron microscopy and electron holography were used to study changes in the MgO tunnel barrier of CoFe/MgO/CoFe magnetic tunnel junctions as a function of annealing and in-situ applied electrical bias. Annealing was found to increase the homogeneity and crystallinity of the MgO tunnel barrier. Cobalt, oxygen and trace amounts of iron diffused into the MgO upon annealing. Annealing also resulted in a reduction of the tunneling barrier height, and decreased the resistance of the annealed MTJ relative to that of the asgrown sample. In-situ off-axis electron holography was employed to image the barrier potential profile of an MTJ directly, with the specimen under electrical bias. Varying the bias voltage from −1.5 V to +1.5 V was found to change the asymmetry of the barrier potential and decrease the effective barrier width as a result of charge accumulation at the MgO-CoFe interface. Introduction Metal-oxide interfaces are the subject of extensive experimental and theoretical research for next generation nano-scale spintronic devices that exploit spin as a degree of freedom for charged electrons. 1 They play a key role in metal-oxide based science and engineering, with applications including magnetic tunnel junctions (MTJs) 2 and other heterogeneous structures such as resistance switching oxides 3 with uses or potentials uses in low-power non-volatile memories. In its simplest form, the MTJ is a trilayer structure consisting of two ferromagnetic (FM) electrode layers separated by an ultra-thin dielectric layer. The electrical resistance across the insulating tunnel barrier is dependent upon the relative orientation of the magnetizations of the two ferromagnetic electrodes. In most cases, the electrical resistance is lower when the magnetization of the two ferromagnetic layers is

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Effect of annealing and applied bias on barrier shape in CoFe/MgO/CoFe tunnel junctions

et al. 2011

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“…Similarly, the combination of SPM with (scanning) transmission electron microscopy (STEM) offers an obvious advantage for gaining atomic level understanding of dynamic processes ( Figure ) 92, 97–99. While in these studies the primary effort is the STEM component, the SPM studies can: (a) for in situ SPM‐STEM studies provide vital information on optimization the experiment ex‐vacuo and hence greatly improving the throughput, and (b) for device characterization provide (unavailable from STEM) information on local relaxation times, field structures, and other functional parameters.…”

Section: Us Department Of Energy Nanoscale Science Research Centersmentioning

confidence: 99%

Scanning Probe Microscopy in US Department of Energy Nanoscale Science Research Centers: Status, Perspectives, and Opportunities

Kalinin

2013

Adv Funct Materials

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“…Recently, Petford-Long and co-workers demonstrated that in situ tunneling experiment can be done in a TEM, on a film crosssection consisting of two ferromagnetic electrodes separated by an insulator. 5,6 The scope of the present work expands on this technique, applying it for the first time, to a series of fully operational,~100ϫ 150 nm 2 MTJs. The motivations for making 100 nm devices are twofold.…”

Section: In Situ Tunneling Measurements In a Transmission Electron MImentioning

confidence: 99%

In situ tunneling measurements in a transmission electron microscope on nanomagnetic tunnel junctions

Lau

Morrow

Read

et al. 2010

Applied Physics Letters

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We showed that a chain of nanomagnetic tunnel junctions (MTJs) devices can be electrically addressed individually, in situ, in a transmission electron microscope, such that transport properties can be in principle, quantitatively correlated with each device’s defects and microstructure. A unique energy barrier was obtained for each device measured. Additionally, in situ tunneling magnetoresistance (TMR) measurements were obtained for a subset of devices. We found that TMR values for our nano-MTJs were generally smaller than TMR in the unpatterned film.

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In situ TEM studies of local transport and structure in nanoscale multilayer films

Cited by 11 publications

References 51 publications

Effect of annealing and applied bias on barrier shape in CoFe/MgO/CoFe tunnel junctions

Effect of annealing and applied bias on barrier shape in CoFe/MgO/CoFe tunnel junctions

Scanning Probe Microscopy in US Department of Energy Nanoscale Science Research Centers: Status, Perspectives, and Opportunities

In situ tunneling measurements in a transmission electron microscope on nanomagnetic tunnel junctions

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